Edwin George

Protection of Mature Oligodendrocytes by Inhibitors of Caspases and Calpains

Mature mouse oligodendrocytes (OLs) are susceptible to death in demyelinating diseases such as multiple sclerosis and in brain injury following neurotrauma, ischemia, or stroke. To understand mechanisms leading to death of mature OLs and develop strategies for protection, we utilized cultures of mature mouse OLs to investigate the role of caspases and calpains in OL cell death mediated by different mechanisms. The agents used were (i) staurosporine, which induces apoptotic death via inhibition of protein kinases; (ii) kainate, which activates non-NMDA glutamate receptors; (iii) thapsigargin, which releases intracellular calcium stores; and (iv) SNAP, which releases active NO species and causes necrotic cell death. Inhibitors blocking primary effector caspases (including caspase 3), the FAS (death receptor)-mediated initiator caspases (including caspase 8), and stress-induced caspases (including caspase 9), were tested for their protective effects. Inhibition of caspases 3, 8, and 9 each robustly protected OLs following insult with staurosporine, thapsigargin, or kainate when added at optimal times. The time of addition of the inhibitors for maximal protection varied with the agent, from 1 h of preincubation before addition of staurosporine to 6 h after addition of kainate. Much less protection was seen for the NO generator SNAP under any condition. The role of calcium in OL death in each model was investigated by chelating extracellular Ca++ with EGTA, and by inhibiting the Ca++-activated calpain proteases. Calcium chelation did not protect against staurosporine, but decreased OL death initiated by kainate, thapsigargin, or NO. The calpain inhibitors PD150606 and calpain inhibitor I protected from cell death initiated by staurosporine, kainate, and thapsigargin, but not from cell death initiated by the NO donor SNAP.

Characterization of retinal architecture in Parkinson's disease.

BACKGROUND Parkinsons disease (PD) is a neurodegenerative disorder associated with dopaminergic cell loss and α-synuclein aggregation in Lewy bodies, which has been demonstrated in the retina. METHODS We performed a spectral-domain optical coherence tomography (OCT) study in patients with PD and healthy controls to measure the peripapillary retinal nerve fiber layer thickness and macular volume. Intra-retinal segmentation was performed to measure the volume of the retinal nerve fiber (RNFL), ganglion cell (GCL), inner plexiform (IPL), inner nuclear (INL), outer plexiform (OPL), and outer nuclear (ONL) layers. Analysis was carried out blinded to the clinical status of study participants. RESULTS 101 PD and 46 healthy control eyes were included in the study. In PD patients, peripapillary retinal nerve fiber layer was not significantly thinner (96.95 μm vs 94.42 μm, p=0.08) but macular volume was (8.58 mm3 vs 8.33 mm3, p=0.0002). Intra-retinal segmentation showed that PD subjects have reduced GCL, IPL, INL and ONL volumes. In contrast, the OPL volume was significantly increased (0.81 mm3 vs 0.78 mm3 p=0.0214). CONCLUSIONS Thickening of the OPL is a novel finding which may correspond to the localization of α-synuclein in the OPL of PD patients. We hypothesize that the enlargement of the OPL may represent a potential biomarker of α-synuclein aggregation in PD. This may have significant clinical implications.

Longitudinal study of the substantia nigra in Parkinson disease: A high-field (1) H-MR spectroscopy imaging study.

The value of biomarkers in early diagnosis and development of therapeutics in Parkinsons disease (PD) is well established.

A strategy for managing flu-like symptoms after botulinum toxin injections

Many adverse effects have been reported following BoNT administration, but most of them are related to the mechanism of action of the toxin, including weakness, ptosis, and dysphagia. Systemic reactions following BoNT are uncommon but primarily comprise nausea, fatigue, malaise, rash, and flu-like symptoms. Flu-like symptoms refers to a group of symptoms that includes fever, cough, sore throat, diffuse myalgias, shivering, chills, malaise, anorexia, and headache [1]. In a recent review, these symptoms occurred in 2–20% of patients receiving BoNT [2]. The reasons for the flu-like symptoms are not clear. Most BoNT preparations contain associated complexing proteins, which may incite an immune response. In fact, patients with flu-like symptoms show an increase in inflammatory cytokines [3]. In our clinics, patients who regularly report poor responses or unusual side effects following BoNT are routinely offered an alternative toxin preparation, with a different makup of proteins. We identified a series of 14 patients who complained of flu-like symptoms within 2 weeks following BoNT injection (Table 1). There were 6 males and 8 females ranging in age from 21 to 80 years. Six had cervical dystonia, three had blepharospasm, and one each had hemidystonia, segmental dystonia, writer’s cramp, hemi-facial spasm and Tourette’s syndrome. All 14 subjects described malaise and diffuse myalgias, some had other symptoms including headache (2), nausea (2), fever (1), and rhinorrhea (1). All experienced these symptoms after more than one treatment session, making chance occurrence of flu-like symptoms after one injection cycle unlikely. Thirteen of the patients were receiving onabotulinumtoxinA when they were identified as having flu-like symptoms, and one was on rimabotulinumtoxinB. All were switched to incobotulinumtoxinA, because the lower levels of complexing proteins may render it less likely to cause immunogenic reactions. All received approximately the same dose equivalents when the product was changed. Ten patients reported complete elimination of flu-like symptoms after switching toxin preparations. The remaining four patients reported a subjective assessment of reduced severity or duration of symptoms. The reduction in symptoms was sustained for at least two further injection cycles, revealing a consistent response. All reported satisfactory therapeutic responses to injections with the second product, similar to the response to their original product. This study was an open-label, unblinded clinical series with a very small number of patients, so the results must be interpreted with caution. It is possible that some patients develop flu-like symptoms from immunoreactions to the toxin protein itself, or from some other component of the toxin preparation. However, the good clinical responses argue against an immunological reaction against the toxin itself. The current series suggests that changing toxin preparations may alleviate flu-like symptoms that sometimes occur as a side-effect of BoNT therapy.