Recent Publications by CFE Educators

We report that section of the sciatic and saphenous nerves, in the hindlimb of the rat, evokes an inflammatory response in the denervated tissue that can be distinguished from the previously described peptide-mediated neurogenic inflammation. This novel form of neurogenic inflammation has a very delayed onset (9.75 +/- 2.1 h, mean +/- S.E.M., n = 8), persists for more than 30 h, and is characterized by a marked neutrophilic cellular infiltrate. These features cannot be mimicked by electrical stimulation of the peripheral nerve and are not prevented by either prior application of local anesthetics to the nerve lesion site or by neonatal treatment with capsaicin.

Retrograde tracing and immunocytochemistry were used to examine the axon collateralization of brainstem serotonin (5-HT) and norepinephrine (NE) cells to the periaqueductal gray (PAG) and spinal cord. Tyrosine hydroxylase (TH)-immunofluorescent neurons which collateralize to the PAG and the cervical spinal cord were found in all brainstem catecholamine cell groups previously shown to contain neurons which project to the spinal cord, including the A5 and A7 cell groups, locus coeruleus, subcoeruleus and the C1 cell group. Many TH-immunofluorescent cells which project to the PAG but not to the spinal cord were also found. The region of the nucleus raphe magnus (NRM) also contained many neurons retrogradely labeled from the PAG. These overlapped with the distribution of spinally projecting 5-HT-immunofluorescent cells in the NRM, however, less than 1% of the PAG projecting cells in this region were 5-HT-immunofluorescent. In contrast, many 5-HT-immunofluorescent cells in the more rostral nucleus raphe pontis and nucleus raphe dorsalis were retrogradely labeled from the PAG but not from the spinal cord. Finally, a population of neurons in the NRM and adjacent reticular formation and in the region of several pontomedullary catecholamine cell groups collateralized to the PAG and spinal cord, but were neither 5-HT nor TH-immunofluorescent. Taken together, these findings raise the possibility that the noradrenergic contribution to the spinal antinociceptive effects produced by PAG electrical stimulation results, in part, from antidromic activation of brainstem noradrenergic neurons that have axon collaterals projecting to the PAG and spinal cord. In contrast, the 5-HT contribution to the spinal antinociceptive effects produced by PAG electrical stimulation is more likely to derive, as previously proposed, from orthodromic activation of raphe-spinal serotonergic axons.

Extracellular levels of serotonin (5-HT), dopamine (DA) and their major metabolites 5-hydroxyindoleacetic acid (5-HIAA), 3,4-dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA), were measured in the lateral hypothalamus of awake, freely moving rats using microdialysis combined with HPLC and electrochemical detection. To characterize the factors which control 5-HT release, the effects of various drugs were assessed. TTX had a reversible inhibitory effect on the basal levels of 5-HT, 5-HIAA, DOPAC and HVA. Infusion of K+ concomitantly increased 5-HT and DA and decreased 5-HIAA and HVA. Imipramine increased extracellular levels of 5-HT and DA and decreased 5-HIAA levels; this effect was TTX-sensitive. Systemic pargyline increased extracellular 5-HT and markedly decreased the metabolic levels. Pargyline pretreatment in the presence of imipramine, infused through the dialysis probe, slowly increased 5-HT levels above that produced by the reuptake blocker alone. Infusion with AMPH produced a dramatic, TTX-insensitive, increase in 5-HT and DA and a decrease in the metabolic levels. These results provide evidence that (1) basal release of 5-HT in the lateral hypothalamus results from neuronal activity, (2) the metabolites in the extracellular fluid derive primarily from intracellular monoamine oxidase (MAO) activity, (3) 5-HT is mainly removed from the extracellular space by a reuptake mechanism, with minimal contribution of an extracellular MAO, and (4) the AMPH-evoked release of 5-HT and DA is a Na+ channel-independent process.

Cigarette smoking is associated with hyperplasia of pulmonary neuroendocrine cells and variably increased levels of bombesin-like peptides in the lower respiratory tract. Because the neuropeptide bombesin is a chemoattractant for monocytes and a mitogen for 3T3 fibroblasts, we hypothesized that an excess of neuroendocrine cells and bombesin-like peptides could contribute to lung inflammation and fibrosis in certain cigarette smokers. Eosinophilic granuloma is a fibrotic lung disease of unknown etiology that in adults occurs almost invariably in cigarette smokers. We quantitated neuroendocrine cells with bombesin-like immunoreactivity in open lung biopsies from patients with eosinophilic granuloma (n = 6) and compared these with cigarette smokers (n = 6) who underwent lung resection for reasons other than primary lung disease. In addition, we compared them with patients with idiopathic pulmonary fibrosis (n = 8), a disease not associated with cigarette smoking. Finally, we also examined the mitogenic effect of bombesin on cultured human adult lung fibroblasts. The patients with eosinophilic granuloma exhibited a 10-fold increase in neuroendocrine cells with bombesin-like immunoreactivity compared to both smokers (P = 0.005) and patients with idiopathic pulmonary fibrosis (P = 0.005). In addition, bombesin produced a significant mitogenic effect on cultured human adult lung fibroblasts at concentrations of 1 nM and above. We conclude that increased numbers of pulmonary neuroendocrine cells with bombesin-like immunoreactivity are commonly found in patients with eosinophilic granuloma and, since bombesin-like peptides are chemotactic for monocytes and mitogenic for human lung fibroblasts, we speculate that neuroendocrine cell hyperplasia may be important in the pathogenesis of eosinophilic granuloma in adult cigarette smokers.

BAL remains a powerful investigative tool. In a short span of 20 yr, it has helped tremendously in understanding some of the aspects of the pathogenesis of diseases involving the lower respiratory tract. To realize its full potential in the diagnosis and management of diseases involving the lower respiratory tract, there is a great need for standardization of the technical aspects of BAL as well as processing and analysis of the BAL cellular- and fluid-phase components. Despite these hurdles, BAL has been found to be diagnostic in several infectious and noninfectious diseases involving the lower respiratory tract, and it provides valuable information that may be helpful in characterizing the prognosis and response to therapy in certain interstitial diseases of the lung. It is expected that with future research, in particular long-term prospective epidemiologic and clinical studies in pneumoconioses and in other interstitial lung disease, BAL will prove more valuable in the diagnosis and management of such disease.

A case of Churg-Strauss vasculitis was studied by high-resolution computed tomography (HRCT) scanning. HRCT scanning demonstrated enlarged, irregular and stellate-shaped arteries, and small patchy opacities were present in the pulmonary parenchyma. These findings correlated with the histologic appearance of the pulmonary parenchyma on open lung biopsy. The arteries were enlarged due to eosinophilic infiltration in the vessel walls, and the adjacent lymphatics were dilated. This observation suggests that HRCT scans may be of value in the evaluation of pulmonary vasculitis because these findings are distinct from those of other diffuse lung lesions.

The mast cell, an immunocompetent cell that contributes to neurogenic inflammation in a variety of tissues, including synovium, is found in close proximity to peripheral terminals of unmyelinated primary afferents and sympathetic postganglionic nerve terminals. In this study we evaluated the hypothesis that the density of mast cells in synovial tissue is dependent on the neural innervation. In normal rats, we found that the density of mast cells in the ankle joint capsule, which is heavily innervated, is greater than in the capsule of the knee, which is less densely innervated. Selective lesions of unmyelinated primary afferents with capsaicin, or of sympathetic postganglionic neurons with guanethidine, produced a significant decrease in mast cells; surgical removal of the parasympathetic ganglia did not significantly affect mast cell density. Finally, the number of mast cells in the synovial joint of spontaneously hypertensive rats, which have increased sympathetic activity, was significantly greater than in normotensive control rats. These observations support the hypothesis that the innervation in the synovial joint of the rat, by unmyelinated afferents and sympathetic efferents, exerts a trophic effect on mast cell density.

Changes in intracellular calcium influence epithelial barrier integrity, but the mechanism of action is unknown. One possibility is that calcium may work by increasing phospholipase A2 (PLA2) and/or phospholipase C (PLG) activity. Measuring the mannitol permeability (Pmann) of cultured monolayers of Madin-Darby canine kidney (MDCK) epithelium cells as a measure of barrier integrity, we found that exposure of the monolayers to 5 and 10 microM A23187 produced an increase in Pmann whereas 1 microM A23187 did not. Exposure of MDCK cells labeled with [3H]arachidonate to A23187 resulted in an increase in both PLA2 activity, as measured by an increase in free fatty acids, and in PLC activity, as measured by an increase in diacylglycerol (DAG). The increase in DAG was due to an increase in phosphatidylcholine-specific PLC activity. The relationship of phospholipolysis to Pmann was evaluated further by the use of mepacrine and dexamethasone. Mepacrine (10 microM) decreased PLA2 activity by 60% but had no effect on increased Pmann after exposure to A23187. Preexposure of the monolayers to dexamethasone (10 microM) blocked both PLA2 activity and PLC activity and also prevented the increase in Pmann after exposure to A23187. To evaluate whether this protective effect of dexamethasone was due to PLC blockade, we incubated the cells with the protein kinase C blocker H-7. Incubation with H-7 offered no protection from increased Pmann after A23187. These results demonstrate that increased intracellular calcium decreases the barrier integrity of epithelium and increases both PLA2 and phosphatidylcholine-specific PLC activity. The increase in Pmann, however, appears to occur through mechanisms other than phospholipase activation.

1. This study examined the effects of the 15-lipoxygenase product of arachidonic acid metabolism, (8R,15S)-dihydroxyicosa-(5E-9,11,13Z)tetraenoic acid (8R,15S-diHETE), on mechanical thresholds and thermal responses of saphenous nerve cutaneous C-fiber nociceptors that innervate the hairy skin of the rat hindpaw. Single C-fiber mechanoheat nociceptors (C-MH) that had von Frey hair (VFH) thresholds greater than 5 g and were activated by a noxious heat stimulus were chosen for study. We also studied the effects of prostaglandin E2 (PGE2), a cyclooxygenase product of arachidonic acid metabolism, on these nociceptors. 2. The 63 C-MHs studied had a conduction velocity of 0.82 +/- 0.03 m/s (mean +/- SE) and a mechanical threshold of 13.4 +/- 2.4 g. In a subgroup of these (n = 24), the thermal threshold was measured as (44 +/- 1 degree C) (mean +/- SE). 3. 8R,15S-diHETE produced a significant decrease in mechanical threshold of C-MHs (n = 33). The 8R,15S-diHETE-induced sensitization of C-MHs to mechanical stimuli was completely antagonized by coadministration with a stereoisomer, 8S,15S-diHETE (n = 10). 4. The mechanical threshold of C-MHs (n = 10), previously injected with the combination of 8R,15S-diHETE and 8S,15S-diHETE, was significantly reduced by a subsequent injection of PGE2. In a separate group of C-MHs (n = 7), PGE2 was co-injected with 8S,15S-diHETE, which failed to antagonize the sensitizing effect of PGE2 on mechanical threshold. 5. 8R,15S-diHETE also sensitized C-MHs (n = 9) to a thermal stimulus consisting of 37 degrees C for 5 min.(ABSTRACT TRUNCATED AT 250 WORDS)