BackgroundAnimal and clinical studies have revealed that focal peripheral nerve axon demyelination is accompanied by nociceptive pain behavior. C-C and C-X-C chemokines and their receptors have been strongly implicated in demyelinating polyneuropathies and persistent pain syndromes. Herein, we studied the degree to which chronic nociceptive pain behavior is correlated with the neuronal expression of chemokines and their receptors following unilateral lysophosphatidylcholine (LPC)-induced focal demyelination of the sciatic nerve in rats.ResultsFocal nerve demyelination increased behavioral reflex responsiveness to mechanical stimuli between postoperative day (POD) 3 and POD28 in both the hindpaw ipsilateral and contralateral to the nerve injury. This behavior was accompanied by a bilateral increase in the numbers of primary sensory neurons expressing the chemokine receptors CCR2, CCR5, and CXCR4 by POD14, with no change in the pattern of CXCR3 expression. Significant increases in the numbers of neurons expressing the chemokines monocyte chemoattractant protein-1 (MCP-1/CCL2), Regulated on Activation, Normal T Expressed and Secreted (RANTES/CCL5) and interferon γ-inducing protein-10 (IP-10/CXCL10) were also evident following nerve injury, although neuronal expression pattern of stromal cell derived factor-1α (SDF1/CXCL12) did not change. Functional studies demonstrated that acutely dissociated sensory neurons derived from LPC-injured animals responded with increased [Ca2+]i following exposure to MCP-1, IP-10, SDF1 and RANTES on POD 14 and 28, but these responses were largely absent by POD35. On days 14 and 28, rats received either saline or a CCR2 receptor antagonist isomer (CCR2 RA-[R]) or its inactive enantiomer (CCR2 RA-[S]) by intraperitoneal (i.p.) injection. CCR2 RA-[R] treatment of nerve-injured rats produced stereospecific bilateral reversal of tactile hyperalgesia.ConclusionThese results suggest that the presence of chemokine signaling by both injured and adjacent, uninjured sensory neurons is correlated with the maintenance phase of a persistent pain state, suggesting that chemokine receptor antagonists may be an important therapeutic intervention for chronic pain.
Nucleoside reverse transcriptase inhibitors (NRTIs) are known to produce painful neuropathies and to enhance states of pain hypersensitivity produced by HIV-1 infection. It has also been observed that in some neuropathic pain models, chemokines and their receptors are upregulated, perhaps contributing to the pain state. In order to understand if chemokines are involved in NRTI-mediated sensory neuropathies, we treated rats with the anti-retroviral drug, 2′,3′-dideoxycytidine (ddC), which is known to produce an extended period of hyperalgesia and allodynia. Using in situ hybridization, we observed that under normal conditions, CXCR4 chemokine receptors were widely expressed by satellite glia in the dorsal root ganglia (DRG) and Schwann cells in the sciatic nerve. A limited number of DRG neurons also expressed CXCR4 receptors. The chemokine SDF-1/ CXCL12 was similarly expressed in glial cells in the DRG and peripheral nerve. Following a single administration of ddC, expression levels of CXCR4 mRNA in glia and neurons and SDF-1 mRNA in glia increased considerably. The functional nature of increased CXCR4 mRNA expression was confirmed by measuring SDF-1 induced [Ca2+]i increases in acutely isolated DRG neurons and glia. In contrast, the expression of the chemokine receptors CCR2 and CCR5 did not change following ddC treatment. Pain hypersensitivity produced by ddC could be inhibited by treatment with the CXCR4 antagonist, AMD3100. Hence, we postulate that NRTIs produce pain hypersensitivity through the upregulation of CXCR4 signaling in the DRG. Increased numbers of CXCR4 receptors would also explain the synergism observed between NRTI treatment and the proalgesic effects of HIV-1 infection.
Adrenal injuries, although an uncommon consequence of abdominal trauma, are important to recognize. If bilateral, adrenal trauma could result in life-threatening adrenal insufficiency. Furthermore, in the setting of trauma, adrenal injury can point to other concomitant injuries and has been associated with overall increased morbidity and mortality. In the past, before the advent of computed tomography (CT), detection was difficult, and the diagnosis was often made only at surgery or postmortem. Today, the diagnosis of adrenal injuries can be quickly and accurately made with CT. This retrospective review was carried out to identify, describe, and analyze different CT appearances of adrenal injuries and correlated with associated injuries and observed clinical context and outcomes. A patient cohort of CT-detected adrenal injuries was identified through a radiology software research tool by searching for keywords in radiology reports. The identified CT scans were reviewed and correlated with the patients' available clinical chart data and follow-up. Between April 1995 and October 2004, 73 cases of CT-detected adrenal injuries were identified, including 48 men and 25 women, with an age range 6 to 90 years and a mean age of 42.7 years. Of the cases, 77% were right-sided, 15% were left-sided, and 8% were bilateral. The causes of injuries were motor vehicle collisions (75%), falls (14%), sports related (4%), and miscellaneous causes (7%). Associated trauma included injuries of the liver (43%), spleen (23%), lung (19%), and kidney (18%), as well as pneumothoraces/hemothoraces (22%). Skeletal injuries included fractures of the ribs, clavicles, and/or scapulae (39%), pelvis and hips (30%), and the spine (23%). Isolated adrenal trauma was seen in only 4% of the cases. The CT findings of adrenal trauma were focal hematoma (30%), indistinct (27%) or enlarged (18%) adrenal gland, gross (15%) or focal (7%) adrenal hemorrhage, and adrenal mass (11%). Associated CT findings included periadrenal fat stranding (93%), retroperitoneal hemorrhage (22%), and thickened diaphragmatic crura (10%). Active adrenal bleeding was seen in one case (1.4%). The incidence of adrenal trauma was estimated to be 0.86%. Surgical management was required only for the associated injuries. The most common CT manifestations of adrenal trauma include focal hematoma, indistinct or ill-defined adrenal gland, adrenal enlargement or mass, and gross or focal adrenal hemorrhage in a normal-sized gland. Periadrenal stranding is very common. Retroperitoneal hemorrhage and crural thickening are also important associated findings. Operative intervention is typically required only for the associated injuries, which commonly accompany adrenal trauma.
level 2b (retrospective cohort).
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