Brain-derived neurotrophic factor stimulates hindlimb stepping and sprouting of cholinergic fibers after spinal cord injury

Neurotrophic factors have been proposed as a therapeutic treatment for traumatic brain and spinal cord injury. The present study determined whether exogenous administration of one such factor, brain-derived neurotrophic factor (BDNF), could effect behavioral recovery and/or histopathological changes after spinal cord injury. Adult rats received a mild or moderate contusion injury or complete transection of the mid-thoracic spinal cord. Immediately thereafter, they were infused intrathecally with vehicle or BDNF for 28 days. Behavioral recovery was evaluated for 6 weeks after injury, at which time the rats were sacrificed and the spinal cord tissue was examined histologically. The infusion of BDNF resulted in acute stimulation of hindlimb activity. These effects included activation of alternating airstepping in injured rats when the hindlimbs were unloaded as well as slight improvements in the rate of recovery in open field locomotion score. BDNF infusion was also associated with enhanced growth of cholinergic fibers at the injury epicenter, but did not affect white matter sparing or density of serotonergic axons at or below the injury site. Based on immunohistochemical detection of BDNF protein distribution, these described effects are likely to be mediated by the activation of cells and axons within the central injury region and the along the peripheral rim of the spinal cord. Together, these findings demonstrate that the exogenous infusion of BDNF after spinal trauma can influence postinjury outcome through mechanisms that include acute stimulation of hindlimb activity and neuritogenesis at the injury site.     

Brain sites involved in the antinociceptive effect of bradykinin in rats

The localization of brain sites where bradykinin (BK) induces its antinociceptive effect in rats, was studied using as index the threshold for the jaw-opening reflex elicited by the dental pulp electrical stimulation test (DPEST). The microinjection of BK into the lateral or fourth cerebral ventricles induced an antinociceptive effect, with Index of Antinociception (IA) of 0.51+/-0.03 and 0.68+/-0.05, respectively. However, microinjections of the peptide into the third ventricle induced a less marked antinociception (IA = 0.28+/-0.08). The brain sites where the microinjection of BK caused an antinociceptive effect were: locus coeruleus, principal nucleus, oral part of the spinal sensorial trigeminal nucleus, and the sensory root of the trigeminal nerve. The antinociceptive effect was more intense when BK (4-16 nmol) was injected into the locus coeruleus. Microinjection of BK (4 nmol) into the fourth ventricle, but not into the locus coeruleus, induced an increase in blood pressure. The microinjection of the peptide into the nucleus tractus solitarius, a site that is also involved in the pressor effect of BK, did not induce an antinociceptive effect. These results indicate that the antinociceptive effect of BK is not related to blood pressure changes. The microinjection of BK into some of the sites involved in the mechanisms of analgaesia, including the periaqueductal gray matter (dorsal, lateral and ventrolateral) and the dorsal raphe nucleus did not induce an antinociceptive effect. The results suggest that the most likely brain sites involved in the antinociceptive effect of BK are the locus coeruleus and the principal sensory trigeminal nucleus. The present results did not exclude the involvement of other brain sites surrounding the lateral and the third ventricles.     

Outcome of transurethral prostatectomy in men over 80 years

Two-hundred-and-twenty-nine men aged between 80 and 97 years (mean 83 years) underwent transurethral prostatectomy (TUR-P) for lower urinary tract symptoms (LUTS). All case records were reviewed. The follow-up period was 6-16 years. One-hundred-and-seven patients underwent operation because of acute urinary retention, and 122 because of chronic retention. The mean weight of tissue removed was 20 g (1-200 g). The perioperative mortality (< 1 month) was 2% (5 patients). Postoperative complications occurred in 21% (49 patients). Reoperation was performed in 11% (26 cases). The result was considered satisfactory in 196 patients (86%). The present data demonstrate that transurethral resection of the prostate in men over 80 years has a good outcome with an acceptable urological complication rate and mortality, and we therefore advocate surgery instead of watchful waiting in the fit patient.     

The use of the chicken embryo screening test and brine shrimp (Artemia salina) bioassays to assess the toxicity of fumonisin B1 mycotoxin

Chicken embryos and brine shrimp naulpii were utilized in short-term toxicity bioassays to assess their sensitivity to the mycotoxin fumonisin B1 (FB1). Fertile chicken eggs (Cobb x) were dosed with FB1 on day 2 of incubation by the injection of 100 microliters of aqueous solution into the air space of each egg. Eggs were incubated with mechanical rotation until hatch, at which time mortality was assessed. Probit transformation of the mortality data produced a linear line of best fit (P < 0.05), from which an LD50 of 52 micrograms FB1/egg, equivalent to a concentration of 1.3 microns hatched in artificial seawater and exposed to FB1 in an optimized 96-well plate assay with a 48 hr mortality endpoint. Probit transformation of the mortality data resulted in an LC50 of 1.7 microns FB1, or 1.2 micrograms FB1/ml. Thus, at the cellular level, both bioassays appeared sensitive to FB1; however, from the standpoint of use as a screening assay, the chicken embryo bioassay is limited by the relatively high dose of FB1 required per egg. It is anticipated that the design and simplicity of the brine shrimp bioassay will accommodate screening for FB1 toxicity in contaminated samples.