Effect of Young's modulus on the detachment force of 7 microm particles.

The detachment force of ground, 7-microm-diameter polyester particles overcoated with clusters of silica having a cluster radius of approximately 100 nm from ceramer substrates with varying Young's moduli has been measured. It was found that the detachment force varied inversely with the Young's modulus of the ceramer. The results are attributed to the role of the silica, acting as asperities on the particles, and the degree of embedment of the particles into the substrate.

Ketamine patient-controlled analgesia for dysesthetic central pain.

STUDY DESIGN: Case report. OBJECTIVES: To describe the first use of intravenous (IV) ketamine as the sole agent in a patient-controlled analgesic delivery system (ie PCA) in a patient with cervical syringomyelia. SETTING: A tertiary-care university teaching hospital in New York City. METHODS: A 41-year-old tetraplegic female on high-dose opioids suffering from intractable dysesthetic central pain received her best pain relief from a low-dose ketamine infusion after failing trials with multiple neuropathic medications. After several weeks of titrating her infusion rate up and down, she was switched to an IV ketamine PCA device. RESULTS: The patient was maintained on an IV ketamine PCA for almost 1 year under the following settings: 2.7 mg/h basal rate; 2.7 mg/h demand dose; 15 min lockout period. Although she continues to report some pain, it has dramatically decreased since the ketamine PCA was instituted, enabling us to significantly reduce her opioid dosage. CONCLUSIONS: Ketamine PCA may be a viable treatment option in patients suffering from intractable central pain. The rationale for this treatment, along with dosing guidelines and possible drawbacks, is discussed.

Plasma anti-serotonin and serotonin anti-idiotypic antibodies are elevated in panic disorder.

The psychoneuroimmunology of panic disorder is relatively unexplored. Alterations within brain stress systems that secondarily influence the immune system have been documented. A recent report indicated elevations of serotonin (5-HT) and ganglioside antibodies in patients with primary fibromyalgia, a condition with documented associations with panic disorder. In line with our interest in dysregulated 5-HT systems in panic disorder (PD), we wished to assess if antibodies directed at the 5-HT system were elevated in patients with PD in comparison to healthy volunteers. Sixty-three patients with panic disorder and 26 healthy volunteers were diagnosed by the SCID. Employing ELISA, we measured anti-5-HT and 5-HT anti-idiotypic antibodies (which are directed at 5-HT receptors). To include all subjects in one experiment, three different batches were run during the ELISA. Plasma serotonin anti-idiotypic antibodies: there was a significant group effect [patients > controls (p = .007)] and batch effect but no interaction. The mean effect size for the three batches was .76. Following Z-score transformation of each separate batch and then combining all scores, patients demonstrated significantly elevated levels of plasma serotonin anti-idiotypic antibodies. Neither sex nor age as covariates affected the significance of the results. There was a strong correlation between anti-serotonin antibody and serotonin anti-idiotypic antibody measures. Plasma anti-serotonin antibodies: there was a significant diagnosis effect [patients > controls (p = .037)]. Mean effect size for the three batches was .52. Upon Z-score transformation, there was a diagnosis effect with antibody elevations in patients. Covaried for sex and age, the result falls below significance to trend levels. The data raise the possibility that psychoimmune dysfunction, specifically related to the 5-HT system, may be present in PD. Potential interruption of 5-HT neurotransmission through autoimmune mechanisms may be of pathophysiologic significance in certain patients with panic disorder. It remains to be demonstrated if the peripheral autoimmunity is representative of CNS 5-HT neuronal alterations. Replication appears warranted.