Similar adverse events from two disparate agents implicate lipid inflammatory mediators for a role in anxiety states.

We recently reported a case in which a 54-year-old male experienced maintenance insomnia, generalized anxiety and panic symptoms associated with consumption of a fish oil supplement enriched in eicosapentaenoic acid (EPA). We report here that the same patient has experienced identical but more severe symptoms in response to the use of the leukotriene receptor antagonist montelukast, in accordance with other cases reported to the Food and Drug Administration. Since omega-3 fatty acids like EPA are precursors for the biosynthesis of eicosanoids including leukotrienes, a common factor to these psychiatric adverse events may be perturbations in this highly complex system of lipid inflammatory mediators.

Insomnia and exacerbation of anxiety associated with high-EPA fish oil supplements after successful treatment of depression.

A 54-year-old male consulted his general practitioner for increasing general anxiety and mild panic attacks despite effective treatment for recurrent major depressive disorder, which included a fish oil supplement enriched in eicosapentaenoic acid (EPA). The patient would awaken suddenly at night with shortness of breath and overwhelming worry. During the daytime, he felt a general, nonspecific anxiety and frequently experienced sympathetic activation upon confronting routine challenges. He also experienced dyspnea-induced feelings of panic. He reported that he stopped taking the fish oil supplements after several more months of symptoms, and his anxiety and insomnia then largely disappeared. Several weeks later, he resumed consumption of high-EPA fish oil at the prior dosage for 2 days. On both nights, the patient reported nighttime awakening similar to the previous episodes, followed by daytime agitation. Since halting the fish oil supplements, the anxiety and insomnia have not returned and his depression remains in remission.

Ionic basis of a mechanotransduction current in adult rat dorsal root ganglion neurons.

Sensory mechanical transduction - necessary for hearing, proprioception, and the senses of touch and pain - remains poorly understood. In somatosensation, even the basic properties of the mechanically sensitive excitatory ionic currents that are assumed to mediate mechanical transduction are largely undescribed. We have recorded, from the soma of rat dorsal root ganglion (DRG) neurons in vitro, whole-cell ionic currents induced by the impact of a piezo-electrically driven glass probe. This transient mechanically activated current was observed in virtually all DRG neurons tested. In ion substitution experiments the current could be carried nonselectively by most cations, including divalent and organic cations, but not by chloride or sulfate ions. In addition, the mechanically activated current carried by monovalent cations was consistently blocked by millimolar concentrations of external calcium or magnesium. Based on these results, the transient mechanical transduction current observed in somatosensory neurons in vitro is mediated by large-pore mechanically gated channels nonselective for cations but impermeable to anions.

Integrin signaling in inflammatory and neuropathic pain in the rat.

Many painful conditions are associated with alterations in the extracellular matrix (ECM) of affected tissues. While several integrins, the receptors for ECM proteins, are present on sensory neurons that mediate pain, the possible role of these cell adhesion molecules in inflammatory or neuropathic pain has not been explored. We found that the intradermal injection of peptide fragments of domains of laminin and fibronectin important for adhesive signaling selectively inhibited the hyperalgesia caused by prostaglandin E2 (PGE2) and epinephrine (EPI), respectively. The block of EPI hyperalgesia was mimicked by other peptides containing the RGD integrin-binding sequence. Monoclonal antibodies (mAbs) against the alpha1 or alpha3 integrin subunits, which participate in laminin binding, selectively blocked PGE2 hyperalgesia, while a mAb against the alpha5 subunit, which participates in fibronectin binding, blocked only EPI-induced hyperalgesia. A mAb against the beta1 integrin subunit, common to receptors for both laminin and fibronectin, inhibited hyperalgesia caused by both agents, as did the knockdown of beta1 integrin expression by intrathecal injection of antisense oligodeoxynucleotides. The laminin peptide, but not the fibronectin peptides, also reversibly abolished the longer lasting inflammatory hyperalgesia induced by carrageenan. Finally, the neuropathic hyperalgesia caused by systemic administration of the cancer chemotherapy agent taxol was reversibly inhibited by antisense knockdown of beta1 integrin. These results strongly implicate specific integrins in the maintenance of inflammatory and neuropathic hyperalgesia.

Role of the sensory neuron cytoskeleton in second messenger signaling for inflammatory pain.

Prostaglandin E(2) (PGE(2)) and epinephrine act directly on nociceptors to produce mechanical hyperalgesia through protein kinase A (PKA) alone or through a combination of PKA, protein kinase C epsilon (PKCepsilon), and extracellular signal-regulated kinase (ERK), respectively. Disruptors of the cytoskeleton (microfilaments, microtubules, and intermediate filaments) markedly attenuated the hyperalgesia in rat paws caused by injection of epinephrine or its downstream mediators. In contrast, the hyperalgesia induced by PGE(2) or its mediators was not affected by any of the cytoskeletal disruptors. These effects were mimicked in vitro, as measured by enhancement of the tetrodotoxin-resistant sodium current. When PGE(2) hyperalgesia was shifted to dependence on PKCepsilon and ERK as well as PKA, as when the tissue is "primed" by prior treatment with carrageenan, it too became dependent on an intact cytoskeleton. Thus, inflammatory mediator-induced mechanical hyperalgesia was differentially dependent on the cytoskeleton such that cytoskeletal dependence correlated with mediation by PKCepsilon and ERK.

Myelotoxicity and dose intensity of chemotherapy: reporting practices from randomized clinical trials.

Delivery of cancer chemotherapy is often limited by myelotoxicity, primarily neutropenia. As part of an effort to create a model to predict the risk of chemotherapy-induced neutropenia, we reviewed the reports of randomized clinical trials with more than 50 patients per arm in early-stage breast cancer (ESBC) and non-Hodgkin's lymphoma (NHL) published between 1990 and 2000. We observed that no hematologic toxicity data were reported in 39% and 34% of the ESBC and NHLtrials, respectively. The remaining trials reported on hematologic toxicity in 16 different ways. When reported, rates of neutropenia, leukopenia, and hematotoxicity varied widely with the same and similar chemotherapy regimens. Dose-intensity data were not reported in 39% and 54% of ESBC and NHL trials, respectively. The majority of the remaining studies reported incomplete dose-intensity data such as percentages of patients completing all cycles or receiving a given percentage of planned dose intensity. Only 28% reported the mean or median relative dose intensity received by patients. Based on this review, we conclude that current practices for reporting chemotherapy treatments are inadequate for describing the risk of chemotherapy to patients or for quantitatively assessing the risk of treatment alternatives. We recommend that standard procedures for documenting and reporting hematologic toxicity and dose intensity in cancer chemotherapy trials be required for publication of chemotherapy trials.