The foreign body response to the Utah Slant Electrode Array in the cat sciatic nerve

As the field of neuroprosthetic research continues to grow, studies describing the foreign body reaction surrounding chronic indwelling electrodes or microelectrode arrays will be critical for assessing biocompatibility. Of particular importance is the reaction surrounding penetrating microelectrodes that are used to stimulate and record from peripheral nerves used for prosthetic control, where such studies on axially penetrating electrodes are limited. Using the Utah Slant Electrode Array and a variety of histological methods, we investigated the foreign body response to the implanted array and its surrounding silicone cuff over long indwelling periods in the cat sciatic nerve. We observed that implanted nerves were associated with increased numbers of activated macrophages at the implant site, as well as distal to the implant, at all time points examined, with the longest observation being 350 days after implantation. We found that implanted cat sciatic nerves undergo a compensatory regenerative response after the initial injury that is accompanied by shifts in nerve fiber composition toward nerve fibers of smaller diameter and evidence of axons growing around microelectrode shafts. Nerve fibers located in fascicles that were not penetrated by the array or were located more than a few hundred microns from the implant appeared normal when examined over the course of a year-long indwelling period.     

Comparison of two abbreviated models of the WISC-R

A comparison of two WISC-R short form models was made to determine the adequacy of each and the possible superiority of one. Data from 192 psychiatric and 200 special education subjects were used to compare Kennedy and Elder's (1982) regression model with Kaufman's (1976) linear equating model. In addition, a regression-derived prediction formula determined from each sample was used to predict FSIQs for the other sample. Correct and incorrect classifications were analyzed for the accuracy of estimate. The percentage of correct classifications for the AAMD Scheme (Heber, 1976) was high for all prediction formulae, and none of the differences was statistically reliable. Correct classification for the Wechsler System (Wechsler, 1974) were more variable, but no differences were statistically significant. Both the Kennedy and Elder, and the Kaufman abbreviated forms attained a high degree of association (K_w = .67 to .89). It was concluded, therefore, that both models were equally effective.     

Long-term male-specific chronic pain via telomere- and p53‑mediated spinal cord cellular senescence

Mice with experimental nerve damage can display long‑lasting neuropathic pain behavior. We show here that 4 months and later after nerve injury, male but not female mice displayed telomere length (TL) reduction and p53‑mediated cellular senescence in the spinal cord, resulting in maintenance of pain and associated with decreased lifespan. Nerve injury increased the number of p53‑positive spinal cord neurons, astrocytes, and microglia, but only in microglia was the increase male‑specific, matching a robust sex specificity of TL reduction in this cell type, which has been previously implicated in male‑specific pain processing. Pain hypersensitivity was reversed by repeated intrathecal administration of a p53‑specific senolytic peptide, only in male mice and only many months after injury. Analysis of UK Biobank data revealed sex-specific relevance of this pathway in humans, featuring male‑specific genetic association of the human p53 locus (TP53) with chronic pain and a male-specific effect of chronic pain on mortality. Our findings demonstrate the existence of a biological mechanism maintaining pain behavior, at least in males, occurring much later than the time span of virtually all extant preclinical studies.     

Prevalence of major depressive disorder in patients receiving beta-blocker therapy versus other medications

Depression is believed to be a common side effect in patients receiving beta-blocker therapy. However, diagnoses of depression defined by current diagnostic criteria may not be more common in patients receiving beta-blockers than in patients with the same medical disorder receiving other medications. Seventy-seven patients undergoing elective cardiac catheterization for evaluation of chest pain received a semi-structured diagnostic psychiatric interview. Twenty-one percent of the patients receiving beta-blockers and 33 percent of the patients receiving medications other than beta-blockers met the current American Psychiatric Association criteria for major depressive disorder (DSM-III) (p = NS). The mean heart rate and state anxiety scores for patients taking beta-blockers were significantly lower than those measured in patients taking medications other than beta-blockers. No other medical or demographic differences were observed between the two groups. Despite the methodologic limitations of the study, there does not appear to be a difference in the point prevalence of depression between patients receiving beta-blockers and those receiving other medications.     

Contrasting effects of recombinant human granulocyte-macrophage colony- stimulating factor (CSF) and granulocyte CSF treatment on the cycling of blood elements in childhood-onset cyclic neutropenia

Recombinant human granulocyte colony-stimulating factor (G-CSF) treatment has been shown to increase average neutrophil counts substantially in patients with childhood-onset cyclic neutropenia (or "cyclic hematopoiesis"), but not to eliminate the cyclic oscillations of neutrophil counts or those of other blood elements (monocytes, platelets, eosinophils, and reticulocytes) that are characteristic of this hematopoietic disorder. Indeed, oscillations of neutrophil counts are amplified during G-CSF treatment. We have compared the effects of recombinant granulocyte-macrophage-CSF (GM-CSF) with those of G-CSF in three patients with this disease (2 men and 1 woman, 17, 30, and 32 years of age). These patients were treated with GM-CSF (2.1 micrograms/kg/day, subcutaneously) for 6 weeks, preceded and followed by 6 to 13 weeks of detailed observation to document changes in the cyclic oscillations of blood neutrophils and other blood elements; two of the patients were subsequently treated with G-CSF (5.0 micrograms/kg/d, subcutaneously) and observed for comparable periods of time. Unlike G-CSF treatment, which increased average neutrophil counts more than 20-fold, GM-CSF increased neutrophil counts only modestly, from 1.6- to 3.9-fold, although eosinophilia of varying prominence was induced in each patient. However, at the same time, GM-CSF treatment dampened or eliminated the multilineage oscillations of circulating blood elements (neutrophils, monocytes, platelets, and/or reticulocytes) in each of the patients. In contrast, G-CSF treatment of the same patients markedly amplified the oscillations of neutrophil counts and caused the cycling of other blood elements (monocytes in particular) to become more distinct. These findings support the conclusion that the distinctive cycling of blood cell production in childhood-onset cyclic neutropenia results from abnormalities in the coordinate regulation of both GM-CSF-responsive, multipotential progenitor cells and G-CSF-responsive, lineage-restricted, neutrophil progenitors.     

Management of acute osteoporotic vertebral fractures: a nonrandomized trial comparing percutaneous vertebroplasty with conservative therapy

PURPOSE: We sought to determine whether percutaneous vertebroplasty--which involves the injection of cement to stabilize a fractured vertebral body--may be an effective treatment for vertebral fracture. METHODS: We enrolled 79 consecutive osteoporotic patients (24 men and 55 women; ages 51 to 93 years) presenting with acute vertebral fractures. Clinical characteristics and bone densitometry were measured at baseline. Pain scores (on a 0 to 25 scale) and levels of function (on a 0 to 20 scale) were recorded on presentation, at 24 hours, at 6 weeks, and 6 to 12 months after therapy. RESULTS: Fifty-five patients (70%) were treated by percutaneous vertebroplasty and 24 (30%) were treated by conservative therapy alone. They were followed for a mean of 215 days (range, 57 to 399 days). The baseline clinical characteristics, bone densitometry, and fracture data were similar in the two groups. Twenty-four hours after vertebroplasty, there was a 53% reduction in pain scores (from 19 to 9; P = 0.0001) and a 29% improvement in physical functioning (from 14 to 18; P = 0.0001), whereas pain scores and physical functioning remained unchanged at 24 hours in the patients treated conservatively (both P = 0.0001 compared with the changes after percutaneous vertebroplasty). Thirteen patients (24%) treated by percutaneous vertebroplasty were able to cease all analgesia after 24 hours (P = 0.0001 compared with none of the 24 patients treated conservatively). Clinical outcomes at 6 weeks and 6 to 12 months were similar in both groups. CONCLUSION: When compared with conservative therapy, percutaneous vertebroplasty results in prompt pain relief and rapid rehabilitation. In experienced hands, it is a safe and effective procedure for treating acute osteoporotic vertebral compression fractures.