The Role of the p14ARF Tumour Suppressor in Promoting Apoptosis

The incidence of melanoma has risen dramatically during the past three decades, yet there has been little improvement in effective treatments for this intractable and aggressive disease. Melanoma tumours are notoriously resistant to apoptosis, a cell suicide program that is activated by most cancer therapies. This thesis explores the role of the melanoma susceptibility gene product p14ARF in promoting cell cycle arrest and apoptosis, in order to resolve the impact of this tumour suppressor in melanomagenesis and melanoma susceptibility. The p14ARF tumour suppressor gene is mutated in almost half of all cancers, and germline mutations in p14ARF confer a greatly increased risk of developing melanoma. The primary function of p14ARF is to relay oncogenic signals to p53, a central regulator of cellular response to stress. There is conflicting evidence regarding the role of p14ARF in promoting apoptosis. Much of the current evidence is based on murine studies, which may not translate accurately to humans due to important differences in animal physiology and the primary sequence and functions of the mouse and human ARF proteins. Furthermore, results from previous studies are often compounded by supra-physiological expression of p14ARF, and are complicated by the fact that p14ARF shares its genomic sequence with the p16INK4a tumour suppressor gene. This study demonstrates that p14ARF expression in human cancer and primary cell lines promotes rapid p53-dependent cell cycle arrest, rather than apoptosis. As p14ARF expression did not induce apoptosis, we investigated if p14ARF could modulate the sensitivity of a cell to apoptosis induced by cytotoxic agents. Using a p14ARF-inducible U2OS osteosarcoma cell line model, we examined the impact of p14ARF expression on the apoptotic response of the cell to a panel of thirteen cytotoxic agents. p14ARF expression increased apoptosis caused by a sub-set of agents, including trichostatin A, sodium butyrate, DRB, Adriamycin and UVB radiation. p14ARF-mediated chemosensitivity was p53- and caspase-dependent, and involved the loss of mitochondrial potential. While loss of mitochondrial potential was dependent on p53, it was not blocked by caspase inhibition, demonstrating that caspases play a role downstream of mitochondrial depolarisation. Inhibition of individual components of the apoptotic program showed that p14ARF-mediated chemosensitivity was not strictly dependent on the pro-apoptotic Bax or Fas proteins. We also investigated whether p14ARF could sensitise melanoma to chemotherapeutics in vivo. We investigated the expression level of p14ARF, p16INK4a and MITFm and mutation status of B-RAF, N-RAS and PTEN in melanomas from 30 patients that had undergone isolated limb infusion - a palliative therapeutic strategy that results in much higher response rates than systemic treatment. Expression of p14ARF did not predict response to the drugs actinomycin D and melphalan . Instead, high expression of p16INK4a and presence of activating N-RAS mutation were independent predictors of response to high doses of these chemotherapeutic drugs. This work suggests that p14ARF analogues may be beneficial adjuncts in cancer therapy, but are unlikely to be effective as single agents. Additionally, p14ARF mimetics will only be effective in tumours with intact p53 signalling. Melanomas frequently carry functional p53, and may be susceptible to this mode of treatment providing the apoptotic pathway downstream of p53 is intact or can be restored

Recombinant human IL-7 administration in mice affects colony-forming units-spleen and lymphoid precursor cell localization and accelerates engraftment of bone marrow transplants

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Visuele hallucinaties bij intacte realiteitstoetsing: fantoomzien.

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Effect of levodopa on orthostatic and postprandial hypotension in elderly Parkinsonian patients.

BACKGROUND: This study describes orthostatic and postprandial hypotension in elderly Parkinsonian patients and evaluates the effect of levodopa therapy on orthostatic and postprandial hypotension in these patients. METHODS: Seventeen elderly patients with a clinical diagnosis of Parkinson's disease or Parkinsonism based on the U.K. Parkinson's Disease Society Brain Bank criteria (age range, 66-84 years) participated in the study. Blood pressure was continuously monitored during standardized standing and meal tests, after starting 125-mg b.i.d. doses of levodopa/benserazide (Madopar) or placebo, in a double-blind, randomized, cross-over design. Seventeen age- and sex-matched healthy subjects served as controls. RESULTS: Orthostatic hypotension was infrequently found in Parkinsonian patients (13%) and healthy subjects (6%; p =.58, between groups), whereas postprandial hypotension was more frequent in Parkinsonian patients (82%) than in healthy subjects (41%; p <.05, between groups). Doses of levodopa/benserazide, administered 2 times per day, did not result in significantly larger blood pressure decreases after standing or eating, or in higher frequencies of orthostatic or postprandial hypotension in the Parkinsonian group. Postprandial hypotension was related to disease severity (r = -.56, p <.05). CONCLUSIONS: Postprandial hypotension, but not orthostatic hypotension, was more common in elderly Parkinsonian patients than in healthy subjects. Therapy with 125-mg b.i.d. doses of levodopa/benserazide did not significantly aggravate orthostatic or postprandial hypotension

Synthesis and comparison of 99mTc-enrofloxacin and 99mTc-ciprofloxacin.

Contains fulltext : 57171.pdf (publisher's version ) (Closed access)The use of (99m)Tc-ciprofloxacin as a tracer for infection and inflammation has been examined and discussed in the literature extensively. Its alleged ability to discriminate between sterile inflammation and bacterial versus nonbacterial infections has led to an intense debate. Other labeled fluoroquinolones might offer better characteristics or may add to a better understanding of the working mechanism of (99m)Tc-ciprofloxacin. The rationale of this work was to determine possible differences in the use of 2 labeled quinolones--that is, (99m)Tc-ciprofloxacin and (99m)Tc-enrofloxacin--as tracers for infection and inflammation in animals. METHODS: Ciprofloxacin and enrofloxacin were labeled with (99m)Tc and characterized. The stability of both preparations was evaluated in serum and in the presence of an excess of cysteine. In vitro binding studies were performed to determine the interaction of the labeled quinolones with bacteria and other cells. Rats with sterile and infectious intramuscular lesions were used to study the scintigraphic properties of the 2 compounds. To assess the specificity of binding to living bacteria, infectious intramuscular lesions of heat-killed Staphylococcus aureus and Candida albicans were used as controls. Imaging was performed with a gamma-camera at 0, 3, 5, and 22 h after injection. RESULTS: The radiochemical purity of both radiolabeled fluoroquinolones exceeded 95% as determined by instant thin-layer chromatography. Both compounds were moderately stable in serum. Binding assays did not show any saturable binding to S. aureus, heat-killed S. aureus, as well as C. albicans. None of the tracers showed specific binding to bacteria. Scintigraphy showed uptake in the infectious lesion at 1 h after injection, which washed out during the next 4 h. Abscess-to-muscle ratios for both preparations were not significantly different for the various infectious or inflammatory lesions studied and did not exceed an average of 4.25 +/- 0.62. CONCLUSION: The study demonstrated that (99m)Tc-ciprofloxacin and (99m)Tc-enrofloxacin do not show preferential binding to living bacteria. In vivo (99m)Tc-enrofloxacin has similar characteristics as (99m)Tc-ciprofloxacin except for differences in uptake in a few normal tissues

The Glial and Mesenchymal Elements of Gliosarcomas Share Similar Genetic Alterations

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Radiotherapy for partially resected spinal ependymomas: a retrospective study of 60 cases.

Ependymomas (Es) and myxopapillary ependymomas (mpEs) are the most common primary tumours of the spinal cord. Recurrence-free survival depends on local control of the tumour. The value of additional radiotherapy (RT) is still a matter of debate. The aim of this retrospective study was to analyse radiotherapy, surgery and the preoperative state with regard to recurrence rate and long-term neurological outcome. Sixty patients with spinal Es (40) and spinal mpEs (20) were included. According to local policy, 14 patients who underwent total resection and 20 patients with incomplete resection were irradiated postoperatively. Total resection was achieved in 34 of the 60 tumours. Preoperative state and long-term outcome was assessed according to a previously published scale. When postoperative RT was applied after partial resection, only 3 of 11 Es and 1 of 9 mpEs recurred. All partially resected non-radiated Es (n=3) and 2 of the 3 partially resected non-radiated mpEs recurred. There was no recurrence after total resection. Only one of 6 patients with disseminated mpEs had clinical symptoms caused by the disseminated tumour. Long-term neurological outcome was related to preoperative conditions with no difference between partially and totally resected tumours. Our study shows that RT is only beneficial for partially resected Es and mpEs. Local recurrence-free survival of spinal Es and mpEs is obtained by total resection. Long-term neurological outcome is related to preoperative conditions. Seeding is seen in mpEs and does not cause clinical symptoms in most of the patients

Radiotherapy for partially resected spinal ependymomas: a retrospective study of 60 cases.

Item does not contain fulltextEpendymomas (Es) and myxopapillary ependymomas (mpEs) are the most common primary tumours of the spinal cord. Recurrence-free survival depends on local control of the tumour. The value of additional radiotherapy (RT) is still a matter of debate. The aim of this retrospective study was to analyse radiotherapy, surgery and the preoperative state with regard to recurrence rate and long-term neurological outcome. Sixty patients with spinal Es (40) and spinal mpEs (20) were included. According to local policy, 14 patients who underwent total resection and 20 patients with incomplete resection were irradiated postoperatively. Total resection was achieved in 34 of the 60 tumours. Preoperative state and long-term outcome was assessed according to a previously published scale. When postoperative RT was applied after partial resection, only 3 of 11 Es and 1 of 9 mpEs recurred. All partially resected non-radiated Es (n=3) and 2 of the 3 partially resected non-radiated mpEs recurred. There was no recurrence after total resection. Only one of 6 patients with disseminated mpEs had clinical symptoms caused by the disseminated tumour. Long-term neurological outcome was related to preoperative conditions with no difference between partially and totally resected tumours. Our study shows that RT is only beneficial for partially resected Es and mpEs. Local recurrence-free survival of spinal Es and mpEs is obtained by total resection. Long-term neurological outcome is related to preoperative conditions. Seeding is seen in mpEs and does not cause clinical symptoms in most of the patients

Extensive epidural cufflike growth of malignant pleural mesothelioma causing spinal cord compression.

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