Stimulation of plasminogen activation by recombinant cellular prion protein is conserved in the NH2-terminal fragment PrP23-110

The cellular prion protein (PrP(c)), tissue-type plasminogen activator (t-PA) and plasminogen are expressed in synaptic membranes in vivo. In the central nervous system the fibrinolytic system is associated with excitotoxin-mediated neurotoxicity and Alzheimer's disease. Recently binding of the disease associated isoform of the prion protein (PrP(Sc)) to plasminogen and stimulation of t-PA activity have been reported. In this study the interaction of PrP(c) and plasminogen was investigated using chromogenic assays in vitro. We found that plasmin is able to cleave recombinant PrP(c) at lysine residue 110 generating an NH(2)-terminal truncated molecule that has previously been described as a major product of PrP(c) metabolism. We further characterized the proteolytic fragments with respect to their ability to stimulate plasminogen activation in vitro. Our results show that the NH(2)-terminal part of PrP(c) spanning amino acids 23-110 (PrP23-110) together with low molecular weight heparin stimulates t-PA mediated plasminogen activation in vitro. The apparent rate constant was increased 57 fold in the presence of 800 nM PrP23-110. Furthermore, we compared the stimulation of t-PA activity by PrP(c) and beta-amyloid peptide (1-42). While the activity of the beta-amyloid was independent of low molecular weight heparin, PrP23-110 was approximately 4- and 37 fold more active than beta-amyloid in the absence or presence of low molecular weight heparin. In summary, plasmin cleaves PrP(c) in vitro and the liberated NH(2)-terminal fragment accelerates plasminogen activation. Cleavage of PrP c has previously been reported. Thus cleavage of PrP(c) enhancing plasminogen activation at the cell surface could constitute a regulatory mechanism of pericellular proteolysis.     

Linear scleroderma associated with progressive brain atrophy

Linear scleroderma (LS) is characterized by scleroatrophic lesions affecting limbs and legs, unilaterally. Neurological involvement may be associated with ipsilateral facial and skull involvement in disorders referred to clinically as LS 'en coup de sabre', and Parry-Romberg syndrome.We report a child with LS presenting with a severe neurological disorder characterized by epilepsy, progressive mental deterioration and a rapid process of atrophy involving the ipsilateral cerebral hemisphere, but not associated with an overlying facial structure involvement. Functional brain studies showed a reduction in the diameter of the left internal carotid and of the left middle cerebral artery. Our observations suggest that neuroimaging studies should be considered in all patients with linear scleroderma, and such studies become necessary when neurological symptoms occur.     

Imaging-guided convection-enhanced delivery and gene therapy of glioblastoma

In a prospective phase I/II clinical study, we treated eight patients suffering from recurrent glioblastoma multiform with stereotactically guided intratumoral convection-enhanced delivery of an HSV-1-tk gene-bearing liposomal vector and systemic ganciclovir. Noninvasive identification of target tissue together with assessment of vector-distribution volume and the effects of gene therapy were achieved using magnetic resonance imaging and positron emission tomography. The treatment was tolerated well without major side effects. In two of eight patients, we observed a greater than 50% reduction of tumor volume and in six of eight patients focal treatment effects. Intracerebral infusion of contrast medium before vector application displayed substantial inhomogeneity of tissue staining indicating the need of test infusions to monitor the mechanical distribution of vectors. Visualization of therapeutic effects on tumor metabolism and documentation of gene expression using positron emission tomography indicated that molecular imaging technology appears to be essential for the further development of biological treatment strategies.     

Severe hypersensitivity pneumonitis associated with anagrelide

OBJECTIVE: To report a case of severe life-threatening hypersensitivity pneumonitis temporally associated with the use of anagrelide in a patient with myeloproliferative disorder. CASE SUMMARY: A 60-year-old white woman with chronic myeloid leukemia who had been treated with hydroxyurea for 7 years was offered anagrelide to control thrombocytosis. She developed severe hypersensitivity pneumonitis soon after the drug was initiated and required intubation and mechanical ventilation. A high-resolution computed tomography scan of the chest demonstrated extensive multifocal ground glass attenuation and patchy alveolar consolidation involving both lungs. Bronchoalveolar lavage revealed a preponderance of lymphocytes, suggesting hypersensitivity phenomenon, but was otherwise negative for malignancy and other causes of interstitial pneumonitis. An objective causality assessment revealed that an adverse drug event was probable. Discontinuation of anagrelide and hydroxyurea, and institution of corticosteroid therapy resulted in dramatic improvement. DISCUSSION: To our knowledge, this is the first case report of severe hypersensitivity pneumonitis closely related to anagrelide therapy. Pulmonary infiltrates have rarely been noted in patients treated with anagrelide. Anagrelide does not depress white blood cell production, causes mild anemia, and is devoid of the leukemogenic potential characteristic of radioactive phosphorus and other alkylating agents. Common adverse effects to anagrelide include headache, nausea, diarrhea, peripheral edema, and palpitations. Frank congestive heart failure and cardiomyopathy have occurred in a small number of patients, but severe pulmonary adverse effects have not emerged as a frequent problem. CONCLUSIONS: Vigilance is advised in patients who develop dyspnea while taking anagrelide and hydroxyurea. Healthcare providers need to be aware of the possibility of the development of serious life-threatening hypersensitivity pneumonitis. These patients may benefit from serial chest X-rays, pulmonary function testing, and echocardiography.     

Systemic co-treatment with alpha-melanocyte stimulating hormone delays hearing loss caused by local cisplatin administration in guinea pigs

It has previously been demonstrated that ototoxicity induced by systemic administration of cisplatin is reduced by concomitant administration of melanocortins, like alpha-melanocyte stimulating hormone (alpha-MSH). However, these experiments were hampered by large interanimal variability. Therefore, we re-investigated the effects of systemically administered alpha-MSH during local (intracochlear) administration of cisplatin. Guinea pigs, implanted with a round-window electrode, allowing daily monitoring of the compound action potentials (CAPs), and a mini-osmotic pump, pumping either 0.5 microl/h physiological saline or cisplatin solution (15 microg/ml), were co-treated daily with a subcutaneous bolus injection of either alpha-MSH (75 microg/kg) or physiological saline for 1 week or until the electrocochleogram showed a persistent decrease in CAP amplitude (40 dB threshold shift at 8 kHz). Next, the animals were sacrificed and the cochleas were processed for histology. After 2-3 days, cisplatin alone caused a threshold shift at all frequencies (2-16 kHz). Co-administration with alpha-MSH consistently delayed the criterion threshold shift by 1 day. When the 40 dB criterion had been reached, similar outer hair cell losses in both the cisplatin/alpha-MSH- and cisplatin/saline-treated groups were observed. This experiment confirms that direct administration of cisplatin into the cochlea results in considerably less interanimal variability than systemic administration and that co-treatment with alpha-MSH delays cisplatin ototoxicity. Since cisplatin was delivered directly to the cochlea, the ameliorating effect of alpha-MSH probably involves a cochlear target.