A robust MRI-compatible system to facilitate highly accurate stereotactic administration of therapeutic agents to targets within the brain of a large animal model

Achieving accurate intracranial electrode or catheter placement is critical in clinical practice in order to maximise the efficacy of deep brain stimulation and drug delivery respectively as well as to minimise side-effects. We have developed a highly accurate and robust method for MRI-guided, stereotactic delivery of catheters and electrodes to deep target structures in the brain of pigs. This study outlines the development of this equipment and animal model. Specifically this system enables reliable head immobilisation, acquisition of high-resolution MR images, precise co-registration of MRI and stereotactic spaces and overall rigidity to facilitate accurate burr hole-generation and catheter implantation.

To demonstrate the utility of this system, in this study a total of twelve catheters were implanted into the putamen of six Large White Landrace pigs. All implants were accurately placed into the putamen. Target accuracy had a mean Euclidean distance of 0.623 mm (standard deviation of 0.33 mm). This method has allowed us to accurately insert fine cannulae, suitable for the administration of therapeutic agents by convection-enhanced delivery (CED), into the brain of pigs. This study provides summary evidence of a robust system for catheter implantation into the brain of a large animal model. We are currently using this stereotactic system, implantation procedure and animal model to develop catheter-based drug delivery systems that will be translated into human clinical trials, as well as to model the distribution of therapeutic agents administered by CED over large volumes of brain.

Riluzole protects against cardiac ischaemia and reperfusion damage via block of the persistent sodium current

BACKGROUND AND PURPOSE

Current strategies to ameliorate cardiac ischaemic and reperfusion damage, including block of the sodium-hydrogen exchanger, are therapeutically ineffective. Here we propose a different approach, block of the persistent sodium current (INaP).

EXPERIMENTAL APPROACH

Left ventricular pressure was measured as an index of functional deficit in isolated, Langendorff perfused, hearts from adult rats, subjected to 30 min global ischaemia and reperfusion with vehicle only (control) or riluzole (1-10 microM) in the perfusate. Cell shortening and intracellular Ca2+ concentrations [Ca2+](i) were measured in adult rat isolated myocytes subjected to hypoxia and re-oxygenation. The block of transient and persistent sodium currents by concentrations of riluzole between 0.01 and 100 microM were assessed in rat isolated myocytes using patch clamp techniques.

KEY RESULTS

In perfused hearts, riluzole produced a concentration-dependent cardioprotective action, with minor protection from 1 microM and produced rapid and almost complete recovery upon reperfusion from 3 and 10 microM. In isolated myocytes, riluzole at 3 and 10 microM greatly attenuated or prevented the hypoxia- and reperfusion-induced rise in [Ca2+](i) and the contractile deficit. In patch clamp experiments, riluzole blocked the persistent sodium current with an IC(50) of 2.7 microM, whereas the block of the transient sodium current was only apparent at concentrations above 30 microM.

CONCLUSIONS AND IMPLICATIONS

Riluzole preferentially blocked INaP and was protective in cardiac ischaemia and reperfusion. Thus block of the persistent sodium current would be a viable method of ameliorating cardiac ischaemic and reperfusion damage.

Implementation of Clinical Supervision: educational preparation and subsequent diary accounts of the practicalities involved, from an Australian mental health [corrected] nursing innovation

Set against the backdrop of several inquiry reports about mental health service provision in Australia, the privately experienced cost of working and coping in contemporary mental health settings, remains poorly understood. Clinical Supervision, a structured staff support arrangement, has shown promise as a positive contribution to the clinical governance agenda and is now found reflected in central policy themes elsewhere in the world. However, the concept of Clinical Supervision remains underdeveloped in Australia. The background to a novel randomized controlled trial, currently in progress in Queensland, Australia, is reported elsewhere. This paper reports on the educational preparation for, and subsequent first-hand testimony of the issues faced by, front-line mental health nursing staff engaged in the implementation of Clinical Supervision, under the auspices of the randomized controlled trial. It is argued here that, in advance of quantitative findings becoming available, several challenges emerge from their supplementary and contemporaneous diary accounts of their experience that may confront Clinical Supervision policy makers, educators, managers and clinicians, anywhere in the world, with immediate effect.

Rationally designed treatment for solid tumors with MAPK pathway activation

2532

Background: Preclinical studies shed light to the mechanism conferring paclitaxel resistance in solid tumors with active Ras/Raf/Mitogen-Activated Protein Kinase (MAPK) pathway, and determined a molecular mechanism by which addition of the proteasome inhibitor bortezomib abrogated this resistance, enabling tumor regression in animals in vivo. Methods: A Phase I study was contacted to determine the MTD of paclitaxel and bortezomib combinatorial treatment. Sixteen patients with refractory solid tumors were treated with weekly paclitaxel and bortezomib. Six patients had NSCLC; 4, colon cancer; 2, pancreatic; 2, melanoma; 1, breast; 1, ovarian. Patients with baseline neuropathy greater than or equal to Grade 1 were excluded. The starting dose was 40 mg/m2 for paclitaxel and 0.7 mg/m2 for bortezomib. A modified continual reassessment method (MCRM) was used for dose escalation with 3-patient cohorts treated at each dose level. The Target Toxicity Level (probability of DLT at the MTD) was set at 25%. Maximum dose escalation was no more than 75% of the previous SED level, if no Grade 3 hematologic toxicity or DLT were observed. Otherwise, the maximum dose escalation was no more than 50% of the previous SED level. The process continued until SED changes were no more than 10% for two consecutive cohorts. Results: The MTD for the combinatorial treatment was reached at 60 mg/m2 paclitaxel and 1.0 mg/m2 bortezomib. Of 15 evaluable patients, 1 patient with paclitaxel-resistant NSCLC had PR and 5 patients (2, NSCLC; 1, pancreatic; 1, colon; 1, ovarian) had stable disease. Median TTP was 2.3 months (0.8 to 6 months). Three NSCLC patients achieved TTP longer than 5 months. The combination of paclitaxel and bortezomib was relatively well tolerated. Paclitaxel PK parameters are being determined, and paraffin-embedded tumor specimens are being evaluated for MAPK pathway activation by IHC for phospho-ERK. Results will be correlated with clinical response. Conclusions: The MTD for the proposed combinatorial treatment is 60 mg/m2 for paclitaxel and 1.0 mg/m2 for bortezomib, and is relatively well tolerated. Combination of paclitaxel with bortezomib is effective in taxane-resistant NSCLC, and worthy of further investigation.

No significant financial relationships to disclose.

Bfl-1/A1 functions, similar to Mcl-1, as a selective tBid and Bak antagonist

The prosurvival Bcl-2-family member Bfl-1/A1 is a transcriptional target of nuclear factor-kappaB (NF-kappaB) that is overexpressed in many human tumors and is a means by which NF-kappaB inhibits apoptosis, but its mode of action is controversial. To better understand how Bfl-1 functions, we investigated its interaction with proapoptotic multidomain proteins Bax and Bak, and the BH3-only proteins Bid and tBid. We demonstrate that in living cells Bfl-1 selectively interacts with Bak and tBid, but not with Bax or Bid. Bfl-1/Bak interaction is functional as Bfl-1 suppressed staurosporine (STS)-induced apoptosis in wild-type and Bax-deficient cells, but not in Bak-/- cells. We also show that Bfl-1 blocks tumor necrosis factor-alpha (TNFalpha)-induced activation of Bax indirectly, via association with tBid. C-terminal deletion decreased Bfl-1's interaction with Bak and tBid and reduced its ability to suppress Bak- and tBid-mediated cell death. These data indicate that Bfl-1 utilizes different mechanisms to suppress apoptosis depending on the stimulus. Bfl-1 associates with tBid to prevent activation of proapoptotic Bax and Bak, and it also interacts directly with Bak to antagonize Bak-mediated cell death, similar to Mcl-1. Thus, part of the protective function of NF-kappaB is to induce Mcl-1-like activity by upregulating Bfl-1.

A phase II trial of 13-cis retinoic acid, interferon, docetaxel, and estramustine (RITE) for the treatment of hormone refractory prostate cancer (HRPC)

15542

Background: Efficacy of chemotherapy for the treatment of HRPC is limited secondary to the development of multiple mechanisms of resistance. In our prior studies, we demonstrated the safety and activity of docetaxel (T) 40 mg/m2 given with 13-cis retinoic acid (R), interferon alpha (I) and estramustine (E), along with a decrease in the expression of the anti-apoptotic protein Bcl-2. To test whether this regimen had clinical activity in HRPC, we conducted a phase II trial with the combination of these drugs. Methods: Eligible patients (pts) received 13-cis retinoic acid 1 mg/kg on days 1 to 4, interferon alfa 6 million units/m2 on days 1 to 4, estramustine 280 mg three times a day on days 1 to 5, and docetaxel 40 mg/m2 on day 2, all repeated every 21 days. Pts had peripheral blood mononuclear cells (PBMCs) obtained prior to therapy and on days 2 through 4 of the first cycle to assess the effect of therapy on the expression of Bcl-2. Results: Nineteen of 20 registered pts (mean age 66) have been treated in this trial. The median pre-treatment PSA was 33.3 ng/mL. A PSA decrease was seen in 13/19 pts (68%) with a mean decrease of 50.3%. A PSA decrease ≥ 50% was seen in 7/19 pts (37%), with an average PSA decrease of 70.4% in these pts. One patient had an objective response (partial remission). The median time to progression (TTP) was 16.3 weeks (range: 3.1 - 132.6 weeks). Three pts remain on study with a median TTP of 25.1 weeks (range: 6.1 - 132.6 weeks). Grade 3 toxicities included 2 pts with hypophosphatemia, 1 patient with neutropenia, and 1 patient with flu-like symptoms. One patient experienced a pulmonary embolism and one patient had a portal vein thrombosis. Common Grade 2 toxicities included fatigue (21%), cytopenias (21%) and GI side effects (16%). There was no treatment-related mortality. Conclusions: These data support the efficacy of the RITE regimen, and the possibility of using alternative Bcl-2 modulating agents in combination with docetaxel in future studies. In addition, long term treatment with low dose docetaxel may be feasible. The assessment of an effect on PBMC Bcl-2 expression is ongoing.

No significant financial relationships to disclose.

Chemotherapy plus cyclosporine A for the treatment of intraocular retinoblastoma: The University of Miami Miller School of Medicine experience

20005

Background: In the past decade chemotherapy and focal control became the standard of care in retinoblastoma. The ideal chemotherapy regimen has not yet been determined. We analyzed the results of treatment at the University of Miami Miller School of Medicine using the regimen carboplatin (20 mg/kg, day 1), vincristine (0.05 mg. /kg, day 1), etoposide (5 mg / kg, days 1 and 2) with or without cyclosporine A (10 mg. /kg over 2 hours followed by 45 mg/kg over 31 hours) every 3–4 weeks. We attempted to maintain peak CSA levels between 2,400 and 6,000 and steady state levels between 2,400 and 4,200 ng/ml. When CSA was given, vincristine was started at 0.0125 mg /kg. The dose was escalated by 25% with each cycle of therapy, as tolerated. Methods: A retrospective analysis was performed in 41 patients diagnosed with bilateral retinoblastoma from Dec 1996 to Jan 2006. Only eyes with intraocular disease (76 eyes) were included in this analysis. Before each cycle of chemotherapy ophthalmologic examination under anesthesia was performed and active tumor and seeding were treated with local ablation using laser therapy. Eyes in which enucleation was planned at diagnosis were excluded from this analysis. Results: Most patients received 9 cycles of chemotherapy. Sixty percent (46/76) of the eyes were treated with chemotherapy and CSA. The eye salvage rate for eyes classified by the International Classification of Retinoblastoma (ICRB) as groups A, B, C and D was 100%. The eye salvage rate for the 21 eyes classified as ICRB group E was 29%. No difference in salvage rate was observed in eyes treated with or without CSA. One patient died from disease progression. Only one patient required radiation therapy to both eyes. To date there have been no reports of development of secondary malignancies. Conclusion: The addition of CSA to the treatment of the eyes classified as ICRB groups A, B, C and D made no difference in the eye salvage rate. Also, we were not able to demonstrate any benefit from the addition of CSA in patients with stage E eyes- although our sample size was quite small. Aggressive focal control and chemotherapy beginning at diagnosis may be the reason for the excellent EFS in group A, B, C and D eyes.

No significant financial relationships to disclose.

Therapeutic starvation and autophagy in prostate cancer: A new paradigm

10530

The metabolic fragility of cancer cells is magnified with the preferential utilization of glycolysis that metabolizes glucose inefficiently rather than oxidative phosphorylation (the “Warburg effect”) and from impaired mechanisms of survival. In fact, one pathway by which cells survive metabolic stress is thought to be autophagy, a catabolic process of organelle digestion, which creates ATP during periods on nutrient limitation. Remarkably, autophagy is often impaired in human prostate cancers, due to either activation of the PI-3 kinase/Akt/mTOR pathway, which normally inhibits autophagy, or through allelic loss of the essential autophagy gene beclin1. This suggests that prostate cancers may be susceptible to metabolic stress that can be exploited therapeutically. Using immortalized mouse epithelial prostate cells, as well as PC-3 and LNCaP cell lines, we demonstrated the cytotoxic effect of 2-deoxyglucose (2DG), as an inhibitor of glycolysis. We found that 2DG induced membrane translocation in cells characteristic of autophagy using a transfected pEGFP-LC3 autophagy marker construct. We then demonstrated that induction of autophagy was dependent on Beclin1 expression in these cell models using Beclin1 siRNA. Based on these data, we initiated a phase I/II clinical trial with 2DG in patients with advanced malignancies and prostate cancer, which is now ongoing. In an effort to develop markers of autophagy for assessment in a clinical trial, we stained a human prostate TMA (>35 patient cores) for Beclin1 by IHC. Beclin1 staining was increased in tumor tissue compared to normal tissue. Staining was imaged and digitized using a 40x volume scan on a high- throughput MedMicro whole slide scanner. The imaged specimens were stored in multi-tiled TIFF format on a redundant array of independent devices (RAID); staining will be analyzed using a color decomposition algorithm and compared to tumor characteristics as we have previously done (Foran DJ et al., IEEE Trans Inf Technol Biomed, 8:89–96, 2004). These data further support the rationale to inhibit metabolism in cancer and the potential importance of autophagy with metabolic approaches to therapy. Further imaging assessment and analysis of markers of autophagy such as Beclin1 are ongoing.

No significant financial relationships to disclose.

Dysplastic naevi with moderate to severe histological dysplasia: a risk factor for melanoma

BACKGROUND

The risk of malignant melanoma associated with histologically dysplastic naevi (HDN) has not been defined. While clinically atypical naevi appear to confer an independent risk of melanoma, no study has evaluated the extent to which HDN are predictive of melanoma.

OBJECTIVES

To estimate the risk of melanoma associated with HDN. Secondarily, the risk associated with number of naevi and large naevi is estimated.

METHODS

We enrolled 80 patients with newly diagnosed melanoma along with 80 spousal controls. After obtaining information on melanoma risk factors and performing a complete cutaneous examination, the most clinically atypical naevus was biopsied in both cases and controls. Histological dysplasia was then assessed independently by 13 dermatopathologists (0, no dysplasia; 1, mild dysplasia; 2, moderate dysplasia; 3, severe dysplasia). The dermatopathologists were blinded as to whether the naevi were from melanoma subjects or controls. Multivariate analyses were performed to determine if there was an independent association between the degree of histological dysplasia in naevi and a personal history of melanoma.

RESULTS

In persons with naevi receiving an average score of > 1 (i.e. naevi considered to have greater than mild histological dysplasia), there was an increased risk of melanoma [odds ratio (OR) 2.60, 95% confidence interval (CI) 0.99-6.86] which persisted after adjustment for confounders (OR 3.99, 95% CI 1.02-15.71). Very few dermatopathologists reliably graded naevi of subjects with melanoma as being more dysplastic than naevi of control subjects. Among the entire group, the interobserver reliability associated with grading histological dysplasia in naevi was poor (weighted kappa 0.28).

CONCLUSIONS

HDN do appear to confer an independent risk of melanoma. However, this result may add more to our biological understanding of melanoma risk than to clinical assessment of risk, because HDN assessed by a single pathologist generally cannot be used to assess risk of melanoma. Future studies should be directed at establishing reproducible, predictive criteria for grading naevi.

Transmural variations in gene expression of stretch-modulated proteins in the rat left ventricle

The properties of left ventricular cardiac myocytes vary transmurally. This may be related to the gradients of stress and strain experienced in vivo across the ventricular wall. We tested the hypothesis that within the rat left ventricle there are transmural differences in the expression of genes for proteins that are involved in mechanosensitive pathways and in associated physiological responses. Real time reverse transcription polymerase chain reaction was used to measure messenger RNA (mRNA) levels of selected targets in sub-epicardial (EPI) and sub-endocardial (ENDO) myocardium. Carbon fibres were attached to single myocytes to stretch them and to record contractility. We observed that the slow positive inotropic response to stretch was not different between EPI and ENDO myocytes and consistent with this, that the mRNA expression of two proteins implicated in the slow response, non-specific cationic mechanosensitive channels (TRPC-1) and Na/H exchanger, were not different. However, mRNA levels of other targets, e.g. the mechanosensitive K⁺ channel TREK-1, Brain Natriuretic Peptide and Endothelin-1 receptor B, were significantly greater in ENDO than EPI. No targets had significantly greater mRNA levels in EPI than ENDO. On the basis of these findings, we suggest that the response of the ventricle to stretch will depend upon both the regional differences in stimuli and the relative expression of the mechanosensitive targets and that generally, stretch sensitivity is predicted to be greater in ENDO.

The BRCA1/BARD1 heterodimer modulates ran-dependent mitotic spindle assembly

The heterodimeric tumor-suppressor complex BRCA1/BARD1 exhibits E3 ubiquitin ligase activity and participates in cell proliferation and chromosome stability control by incompletely defined mechanisms. Here we show that, in both mammalian cells and Xenopus egg extracts, BRCA1/BARD1 is required for mitotic spindle-pole assembly and for accumulation of TPX2, a major spindle organizer and Ran target, on spindle poles. This function is centrosome independent, operates downstream of Ran GTPase, and depends upon BRCA1/BARD1 E3 ubiquitin ligase activity. Xenopus BRCA1/BARD1 forms endogenous complexes with three spindle-pole proteins, TPX2, NuMA, and XRHAMM--a known TPX2 partner--and specifically attenuates XRHAMM function. These observations reveal a previously unrecognized function of BRCA1/BARD1 in mitotic spindle assembly that likely contributes to its role in chromosome stability control and tumor suppression.

Diabetes and the risk of prostate cancer: the role of diabetes treatment and complications

Epidemiologic evidence suggests diabetic men have a slightly lower prostate cancer risk than non-diabetic men. We examined this association in a prospective cohort study of 35 239 men, 50-76 years old, in Washington State who completed a baseline questionnaire between 2000 and 2002. Incident prostate cancers as of 31 December 2004 were identified through the SEER registry. Diabetic men had a slightly lower risk of prostate cancer than non-diabetic men (hazard ratio (HR) 0.83, 95% confidence interval (CI) 0.64-1.07). Insulin users overall and insulin users with diabetic complications had decreased risks, compared to non-diabetic men (HR 0.49, 95% CI 0.26-0.92) and (HR 0.36, 95% CI 0.15-0.87), respectively. Oral medication use for diabetes was not associated with prostate cancer. Insulin is likely a marker of severity of diabetes. Future studies of this association should consider diabetes type, treatment, severity, complications and biomarkers.