Recent Publications by CFE Educators

Although very sensitive chromogens have been adapted for localization of horseradish peroxidase in anterograde and retrograde tracing studies, they have not been successfully applied in immunocytochemical studies. This report describes a protocol which uses benzidine dihydrochloride (BDHC) as the chromogen for light (LM) and electron microscopic (EM) immunocytochemical studies. The protocol is comparable to that used for tetramethylbenzidine, except that the pH of the reaction is above 6.0. At the LM level, the BDHC reaction product is bluish-green and crystalline. Both the color and form of the product are readily distinguished from the reddish-brown DAB reaction product. LM double-labeling studies are therefore feasible. The use of BDHC also increases significantly the sensitivity of the immunoreaction. Higher fixative concentrations can be used, less detergent is necessary, and higher primary antibody dilutions are possible. By osmicating at 45 degrees C in an s-collidine buffer it is possible to preserve the soluble BDHC reaction product for EM analysis. Immunoreactive cells are particularly well labeled with this new protocol. The BDHC crystals are easily detected at the EM level and can be distinguished from flocculent DAB reaction product. This feature makes EM double-labeling studies possible.

Although gold is one of the few therapeutic agents that has been proven effective in producing remission in patients with rheumatoid arthritis, its mechanism of action is unknown. Since nociceptive afferent and sympathetic efferent fibers of the peripheral nervous system contribute to the pathophysiology of inflammation, and since a known side effect of gold therapy is a polyneuropathy, we tested the hypothesis that gold is toxic to small-diameter peripheral nerve fibers in the rat. We found that prolonged treatment with gold, at the same dosage reported to be effective against adjuvant-induced arthritis in the rat, produced a significant decrease in the numbers of unmyelinated, but not of myelinated, axons. Gold treatment also elevated nociceptive thresholds in both articular and nonarticular structures. These results suggest that gold produces an antiinflammatory effect on arthritis by a neurotoxic effect on the peripheral nerves involved in neurogenic inflammation.

This study used antisera directed against glutamic acid decarboxylase (GAD), the biosynthetic enzyme for gamma-aminobutyric acid (GABA), to examine the light- and electron-microscopic distribution of presumed GABA-ergic synapses in the medullary homologue of the cat spinal dorsal horn, the trigeminal nucleus caudalis. At the light-microscopic level, immunoreactive terminals were concentrated in the superficial dorsal horn, laminae I and II. Colchicine was generally ineffective in revealing the distribution of cell bodies. However, in two successful cases, the majority of labeled cells were found in the magnocellular layer, ventral to the substantia gelatinosa, a region that had a lower density of immunoreactive terminals. Other labeled neurons were scattered in laminae I and II. A variety of synaptic arrangements were found at the electron-microscopic level. These derived from two types of labeled terminals. One contained both small round vesicles and large dense-cored vesicles. The second contained small round and pleomorphic vesicles. Some immunoreactive GAD terminals contained a few flat vesicles. Labeled terminals predominantly formed axodendritic synapses, via symmetrical contacts. Several axoaxonic arrangements were also observed. In most cases, the GAD terminal (which did not contain dense-cored vesicles) was presynaptic to another vesicle-containing profile, including the scalloped central terminal thought to derive from primary afferents. Another population of labeled GAD terminals was found postsynaptic to unlabeled vesicle-containing profiles, including central terminals. These data indicate that inhibitory GABA-ergic controls in the trigeminal nucleus caudalis involve both presynaptic and postsynaptic mechanisms and are probably mediated via direct contacts onto ascending projection neurons, as well as via synaptic contacts onto nociceptive primary afferent fibers. The transmission of nociceptive messages by neurons of the spinal cord dorsal horn and trigeminal nucleus caudalis is subject to a variety of segmental and supraspinal controls. Pharmacological and electrophysiological studies have implicated the biogenic amines serotonin and norepinephrine, and the endogenous opioid peptides enkephalin and dynorphin, in those controls (Basbaum and Fields, 1978, 1984; Basbaum et al., 1983; Basbaum, 1985).(ABSTRACT TRUNCATED AT 400 WORDS)

Immunocytochemical analysis of the distribution of dynorphin B terminals in the sacral spinal cord of the cat revealed a pattern of staining very similar to that produced with antisera directed against the primary afferent derived, putative neurotransmitter, vasoactive intestinal polypeptide. Labeled axons and terminals were concentrated in lamina I and V and there was dense fiber staining in the tract of Lissauer. Of particular interest was the presence of immunoreactive axons in attached dorsal rootlets. To specifically focus on the possibility that some of the sacral primary afferent fibers are dynorphin-immunoreactive, we first tried to increase perikaryal labeling in the sacral dorsal root ganglia by topical treatment with colchicine. This did not produce immunoreactive labeling of cell bodies in the ganglia. Unilateral multiple dorsal rhizotomy (L5 to coccygeal 1), however, significantly decreased the staining of dynorphin-immunoreactive axons and terminals in the tract of Lissauer and in the dorsal horn of sacral segments ipsilateral to the deafferentation. No changes were detected in the lumbar cord. Finally, radioimmunoassay of caudal lumbar and sacral dorsal root ganglia was performed. Measurable immunoreactivity was found in all ganglia assayed, but, consistent with the histochemical analysis, sacral ganglia contained the highest concentration of immunoreactive dynorphin B. These data indicate that a significant component of the sacral spinal cord dynorphin terminal immunoreactivity derives from primary afferent fibers.(ABSTRACT TRUNCATED AT 250 WORDS)

Patients with idiopathic pulmonary fibrosis (IPF) are often cigarette smokers and are often being treated with corticosteroids at the time of bronchoalveolar lavage. We addressed the question of whether or not the bronchoalveolar lavage fluid (BALF) neutrophil content of patients with IPF undergoes changes in smokers different from those in nonsmokers after institution of corticosteroids. Eighteen patients were studied (10 smokers and 8 nonsmokers). Fourteen patients (6 smokers and 8 nonsmokers) were treated orally with prednisone. The histologic assessment of alveolar inflammation and inflammatory small airways disease was no different in smokers than in nonsmokers. None of the smokers treated with prednisone had pathologic evidence of emphysema in addition to IPF. Five of 6 smokers showed an increase in BALF neutrophils after 3 months of prednisone (p less than 0.05), whereas the nonsmokers' BALF neutrophils decreased or remained unchanged. This increase in BALF neutrophils in smokers was not associated with concomitant or subsequent clinical deterioration but, in fact, with clinical improvement after 3 months of therapy. These data indicate that the combination of cigarette smoking and corticosteroid therapy influences the BALF neutrophil content in patients with IPF and suggest that interval changes in BALF neutrophil content may not reflect the status of the inflammatory process or structural derangements in the lungs of some patients with IPF.

In order to develop a reproducible, quantifiable means of assessment of the clinical status of patients with idiopathic pulmonary fibrosis (IPF), a composite clinical-radiographic-physiologic (CRP) scoring system was devised, using 7 variables: dyspnea, chest radiograph, spirometry, lung volume, diffusion capacity, resting alveolar-arterial PO2, and exercise O2 saturation. To assess this scoring system, we examined the relationships between CRP scores and histopathologic findings, including a cellular pathology score composed of abnormalities deemed to be potentially reversible, a fibrotic pathology score based on abnormalities felt to be essentially irreversible, and an index of overall pathologic derangement (total pathology score), derived from the sum of the cellular and fibrotic scores. The initial CRP determination at the time of open lung biopsy correlated significantly with the total pathology score (r = 0.61, p less than 0.001). The CRP score determined after 6 months of corticosteroid therapy showed a significant correlation with the fibrotic pathology score present on open lung biopsy (r = 0.76, p less than 0.001). The change in CRP after 6 months of corticosteroid therapy tended to reflect the cellular histopathologic component of the open lung biopsy (r = -0.43, p less than 0.10). Moreover, in none of these relationships did any individual component of the CRP score correlate better with the respective histopathologic index than did the CRP score itself. These data suggest that this CRP score is useful for the estimation of the severity of underlying pathologic derangement and for the longitudinal quantitative assessment of clinical impairment in patients with IPF.

Electrophysiological and immunocytochemical techniques were used in the abdominal ganglion of Aplysia to identify neurons containing immunoreactive FMRFamide. Large numbers of neurons were immunoreactive for FMRFamide, including R2, L2, L3, L4, L5, L6, 2 cells tentatively identified as L12 and L13, and a previously unidentified cluster on the ventral surface of the right lower quadrant. There was also heavy labelling of fibers, often with beaded varicosities, throughout the neuropil, the cell layers, and the sheath overlying the ganglion. This data provides further evidence that FMRFamide is an important neurotransmitter in Aplysia. The demonstration of immunoreactive FMRFamide in the giant cholinergic neurons R2 and LP1(1) suggests that these well-studied and experimentally convenient cells use acetylcholine and an FMRFamide-like peptide as cotransmitters.

Monitoring the quality of well-established multisite clerkships can be aided by the use of trend analysis and graphic-oriented presentations. Five years of data on student performance, experience, and perceptions are reported for an obstetrics and gynecology clerkship offered at eight geographically dispersed sites. Of the five measures of student performance, two (final written and oral examinations) showed major changes. Trends also appeared in student participation in deliveries and student ratings of teaching over time. The results of these analyses were communicated to faculty at each site and used to make improvements in the clerkship. The implications and use of these longitudinal evaluation procedures are discussed.

Using immunocytochemistry, we have identified important differences in the distribution of immunoreactive dynorphin and enkephalin cells and terminals in the trigeminal nucleus caudalis and in the spinal dorsal horn of the cat. Dynorphin immunoreactive processes are more closely associated with those regions of cord that process nociceptive information, specifically laminae I and V. Enkephalin neurons and terminals are more widespread. Based on the staining pattern with an antiserum to the octapeptide-metenkephalin-arg-gly-leu, we suggest that the dense enkephalin terminal immunoreactivity in the inner part of the substantia gelatinosa derives from cells in lamina III. There are also significant differences in the anatomical relationship of the two opioid peptides with the organization of parasympathetic autonomic preganglionic neurons. The functional significance of these observations must await physiological analysis; nevertheless, it is almost certain that differences will be found and that these will be important in understanding the mechanisms through which exogenous opiates and a variety of descending control systems exert their effects on spinal cord neurons.