Induction of corticospinal regeneration by lentiviral trkB-induced Erk activation

Several experimental manipulations of the CNS environment successfully elicit regeneration of sensory and bulbospinal motor axons but fail to elicit regeneration of corticospinal axons, suggesting that cell-intrinsic mechanisms limit the regeneration of this critical class of motor neurons. We hypothesized that enhancement of intrinsic neuronal growth mechanisms would enable adult corticospinal motor axon regeneration. Lentiviral vectors were used to overexpress the BDNF receptor trkB in layer V corticospinal motor neurons. After subcortical axotomy, trkB transduction induced corticospinal axon regeneration into subcortical lesion sites expressing BDNF. In the absence of trkB overexpression, no regeneration occurred. Selective deletion of canonical, trkB-mediated neurite outgrowth signaling by mutation of the Shc/FRS-2 activation domain prohibited Erk activation and eliminated regeneration. These findings support the hypothesis that the refractory regenerative state of adult corticospinal axons can be attributed at least in part to neuron-intrinsic mechanisms, and that activation of ERK signaling can elicit corticospinal tract regeneration.     

Future of stereotactic intervention in lung cancer

With the recent advances in technology, highly sophisticated hardware (linear accelerators specially designed for Stereotactic Radio-Surgery or Stereotactic Body Radiation Therapy (SBRT) using novel image guidance prior to and during the procedure) and equally sophisticated planning treatment software (static and dynamic Intensity Modulated Radiation Therapy) became available, allowing for ablative doses to be delivered with an accuracy of less than 1 mm to targets which are non-static due to respiratory motion.     

Combining factors on protein and gene level to predict radioresponse in head and neck cancer cell lines

J Oral Pathol Med (2011) 40 : 739–746 Background: Radiotherapy is the main therapy for head and neck squamous cell carcinoma (HNSCC); however, treatment resistance and local recurrence are significant problems, highlighting the need for predictive markers. In this study, we evaluated selected proteins, mutations, and single nucleotide polymorphisms (SNPs) involved in apoptosis, cell proliferation, and DNA repair alone or combined as predictive markers for radioresponse in 42 HNSCC cell lines. Methods: The expression of epidermal growth factor receptor, survivin, Bax, Bcl‐2, Bcl‐X_L, cyclooxygenase‐2 (COX‐2), and heat shock protein 70 was analyzed by ELISA. Furthermore, mutations and SNPs in the p53 gene as well as SNPs in the MDM2, XRCC1, and XRCC3 genes were analyzed for their relation to radioresponse. To enable the evaluation of the predictive value of several factors combined, each cell line was allocated points based on the number of negative points (NNP) system, and the NNP sum was correlated with radioresponse. Results: Survivin was the only factor that alone was significantly correlated with the intrinsic radiosensitivity (IR; r = 0.36, P = 0.02). The combination of survivin, Bax, Bcl‐2, Bcl‐X_L, COX‐2, and the p53 Arg72Pro polymorphism was found to most strongly correlate with radioresponse (r = 0.553, P < 0.001). Conclusion: These data indicate that the IR of 42 HNSCC cell lines can be predicted by a panel of factors on both the protein and gene levels. Moreover, among the investigated factors, survivin was the most promising biomarker of radioresponse.     

Comparison between serial skin-prick tests and specific serum immunoglobulin E to mite allergens

Sensitization to dust mite allergens can be determined by means of a skin-prick test (SPT) or by measurement of specific IgE antibodies in serum (sIgE). In our study, concordance of the results of both methods was analyzed on the basis of reproducible SPT results. Three consecutive SPTs were performed on 138 school children (age 6–8 years) at one-year intervals. SIgE was determined at the end of a two-year observation period. Seven common inhalant allergens (Dpt, Df, birch pollens, hazel pollens, grass pollens and cat and dog dander) were analyzed. The majority of subjects with positive SPT reactions to the respective allergen also showed sIgE (Dpt: 82/86; Df: 53/53; cat dander: 31/32; dog dander: 6/9; birch pollens: 29/31; hazel pollens: 22/22; grass pollens: 37/37). A significant correlation between the SPT [weal diameter (P₁) or allergen/histamine ratio (P₂)] and sIgE was found for Dpt (P₁ = 0.004/P₂ = 0.016), birch pollens (P₁ = 0.002/P₂ = 0.0001) and grass pollens (P₁ = 0.0005/P₂ = 0.0001). There was also a significant correlation between sIgE to Dpt and to either Der p 1 (p = 0.0001) or Der p 2 (p = 0.0001), as well as between sIgE of both major allergens (p = 0.0001). In the analysis of co-sensitization of Dpt and Df, most subjects sensitized to Dpt were also sensitized to Df (57/91). Children with sIgE to Dpt (n = 87) usually showed sIgE to Df (n = 83). In this study, SPT and sIgE results are concordant and appear equivalent when using reproducible SPTs. Therefore, in the case of a positive Dpt result, additional testing for sensitization to Df can be regarded as redundant when Dpt and Df are the major contributors to the allergen content of house dust.     

Intrinsic tissue fluorescence in an organotypic perfusion culture of the porcine ocular fundus exposed to blue light and free radicals

BACKGROUND: A wide variety of pathological pathways may result in age-related macular degeneration. Because of its complexity, there is no comprehensive model of the disease yet. One key feature is the accumulation of the autofluorescent pigment lipofuscin in the retinal pigment epithelium (RPE). Thus, we developed an organotypic perfusion culture model of the porcine ocular fundus, generating lipofuscin under exposure to blue light and hydrogen peroxide. METHODS: Porcine fundi (choroid, Bruch's membrane, RPE, and retina) were explanted in toto, transferred into a perfusion culture chamber, perfused with cell culture medium and kept at 37 degrees C. Free radical stress was induced by supplementation of H(2)O(2), and/or the specimens were exposed to blue light, or kept untreated as controls. After a culture period of 7 days, the specimens were subject to microscopic inspection, histology, fluorescence microscopy, and measurement of fluorescence spectra as well as fluorescence decay times. RESULTS: Histology showed atrophic ganglion cells and rod outer segments. All other tissue structures were morphologically intact. Compared to the controls, RPE and retina exposed to light showed increased fluorescence, which was shifted towards shorter wavelengths. The fluorescence spectra and decays resembled that of lipofuscin granules isolated from human donor eyes. HPLC analysis revealed the abundance of the lipofuscin component N-retinylidene-N-retinylethanolamine (A2E), its precursor products, as well as two new, green-emitting fluorophores. CONCLUSIONS: Porcine ocular fundi were successfully preserved in an organotypic perfusion culture for 7 days, and exhibited remarkable autofluorescence after light and free radical exposure, making the model suitable for investigations of lipofuscinogenesis.     

Effect of adenosine receptor agonists and other compounds on cyclic AMP accumulation in forskolin-treated hippocampal slices

The effect of adenosine analogues and some putative neurotransmitters have been studied on cyclic AMP accumulation in rat hippocampal slices treated with the adenylate cyclase activator forskolin. The effects of PGE2 and histamine were potentiated by forskolin (0.1 microM). Isoprenaline and NECA had essentially additive effects with 0.1 microM forskolin and serotonin (above 10(-4) M) inhibited forskolin-stimulated cyclic AMP accumulation. The A1-adenosine receptor selective adenosine analogue R-PIA inhibited forskolin stimulated cyclic AMP accumulation in low doses and stimulated in high. NECA, adenosine and 2-chloroadenosine uniformly stimulated cyclic AMP accumulation. 2',5'-dideoxyadenosine inhibited, but only at high concentrations. Both the stimulatory and the inhibitory effects of R-PIA were antagonized by 8-phenyltheophylline (10 microM). Enprofylline (100 microM) selectively inhibited the stimulatory effect. In the presence of enprofylline both 2-chloroadenosine showed an inhibitory effect on cyclic AMP accumulation. It is concluded that the forskolin-treated rat hippocampal slice is a useful preparation to study both stimulatory and inhibitory effects of transmitters and modulators on adenylate cyclase. The results also show that the rat hippocampus has both A1-receptors that are linked to inhibition of cyclic AMP accumulation and A2-receptors that are linked to stimulation. Furthermore, enprofylline is shown to selectively antagonize the stimulatory response, revealing inhibitory effects of compounds such as 2-chloroadenosine and adenosine.     

COMT inhibition with tolcapone does not affect carbidopa pharmacokinetics in parkinsonian patients in levodopa/carbidopa (Sinemet®)

AIMS: Tolcapone is a novel catechol-O-methyltransferase (COMT) inhibitor used as an adjunct to levodopa/carbidopa or levodopa/benserazide therapy to improve treatment of Parkinson's disease. The aim of the current study was to investigate the potential effect of tolcapone on the pharmacokinetics of carbidopa. METHODS: This was an open-label study in 12 parkinsonian patients receiving optimal levodopa/carbidopa therapy and tolcapone 200 mg three times daily for 6 weeks. Blood samples were taken at baseline (i.e. before the first tolcapone intake) and after 1-2 weeks and 6 weeks so that carbidopa pharmacokinetics before and during tolcapone treatment could be assessed. RESULTS: No changes in any pharmacokinetic parameters of carbidopa were observed. The mean AUC(0,tau) and Cmax values at baseline were 0.39 microg ml-1 h and 0. 14 microg ml-1, respectively. During tolcapone treatment these values were on average 0.35 microg ml-1 h (AUC(0,tau), week 1-2), 0. 34 microg ml-1 h (AUC(0,tau), week 6 and 0.13 microg ml-1 (Cmax, weeks 1-2 and 6). tmax remained unchanged (approx. 2 h). CONCLUSIONS: These results indicate that tolcapone does not affect carbidopa elimination and that no interaction of any clinical relevance occurs between tolcapone and carbidopa.