Effect of Palmitoyl Nanogold Particles on the Subzero Thermal Properties of Phosphate Buffered Saline Solutions

Extensive studies document the effect of nanoparticles on thermal properties of fluids, such as thermal conductivity, although very few exist at subzero temperatures. The current study reports the effect of 1.4 nm palmitoyl nanogold particles (NPs) on the freezing properties of phosphate buffered saline solutions with the help of a differential scanning calorimeter. The results show that NPs have a complex effect on the two properties of interest, i.e., homogeneous nucleation temperature (Th) and phase change temperature (or the melting temperature, Tm). The homogeneous nucleation temperature was significantly elevated at a concentration of 1 nM/ml NPs with 0.167% (v/v) DMSO, and 3 nM/ml NPs with 0.50% (v/v) DMSO concentration, whereas at the other concentrations (1.2 nM/ml NPs with 0.20% DMSO, 1.5 nM/ml NPs with 0.25% DSMO, and 6 nM/ml NPs with 1% DMSO), it was significantly depressed. A similar phenomenon was also noticed in the measured values of the melting temperature of PBS solutions.

Germline and somatic NF1 gene mutation spectrum in NF1-associated malignant peripheral nerve sheath tumors (MPNSTs)

About 10% of neurofibromatosis type 1 (NF1) patients develop malignant peripheral nerve sheath tumors (MPNSTs) and represent considerable patient morbidity and mortality. Elucidation of the genetic mechanisms by which inherited and acquired NF1 disease gene variants lead to MPNST development is important. A study was undertaken to identify the constitutional and somatic NF1 mutations in 34 MPNSTs from 27 NF1 patients. The NF1 germline mutations identified in 22 lymphocytes DNA from these patients included seven novel mutations and a large 1.4-Mb deletion. The NF1 germline mutation spectrum was similar to that previously identified in adult NF1 patients without MPNST. Somatic NF1 mutations were identified in tumor DNA from 31 out of 34 MPNSTs, of which 28 were large genomic deletions. The high prevalence (>90%) of such deletions in MPNST contrast with the =or<20% found in benign neurofibromas and is indicative of the involvement of different mutational mechanisms in these tumors. Coinactivation of the TP53 gene by deletion, or by point mutation along with NF1 gene inactivation, is known to exacerbate disease symptoms in NF1, therefore TP53 gene inactivation was screened. DNA from 20 tumors showed evidence for loss of heterozygosity (LOH) across the TP53 region in 11 samples, with novel TP53 point mutations in four tumors.

The warburg effect and tumour cell survival in human GBMs

Introduction: GBMs are resistant to apoptosis induced by the hypoxic microenvironment and standard therapies including radiation and chemotherapy. We postulate that the Warburg effect, a preferential glycolytic phenotype of tumor cells even under aerobic conditions, plays a role in these aberrant pro-survival signals. In this study we quantitatively examined the expression profile of hypoxia-related glycolytic genes within pathologically- and MRI-defined “centre” and “periphery” of GBMs. We hypothesize that expression of hypoxia-induced glycolytic genes, particularly hexokinase 2 (HK2), favours cell survival and modulates resistance to tumour cell apoptosis by inhibiting the intrinsic mitochondrial apoptotic pathway. Methods: GBM patients underwent conventional T1-weighted contrast-enhanced MRI and MR spectroscopy studies on a 3.0T GE scanner, prior to stereotactic sampling (formalin and frozen) from regions which were T1-Gad enhancing (“centre”) and T2-positive, T1-Gad negative (“periphery”). Real-time qRT-PCR was performed to quantify regional gene expression of glycolytic genes including HK2. In vitro functional studies were performed in U87 and U373 GBM cell lines grown in normoxic (21% pO2) and hypoxic (< 1%pO2) conditions, transfected with HK2 siRNA followed by measurement of cell proliferation (BrdU), apoptosis (activated caspase 3/7, TUNEL, cytochrome c release) and viability (MTS assay). Results: There exists a differential expression profile of glycolytic enzymes between the hypoxic center and relatively normoxic periphery of GBMs. Under hypoxic conditions, there is increased expression of HK2 at the mitochondrial membrane in GBM cells. In vitro HK2 knockdown led to decreased cell survival and increased apoptosis via the intrinsic mitochondrial pathway, as seen by increased mitochondrial release of cytochrome-C. Conclusions: Increased expression of HK2 in the centre of GBMs promotes cell survival and confers resistance to apoptosis, as confirmed by in vitro studies. In vivo intracranial xenograft studies with injection of HK2-shRNA are currently being performed. HK2 and possibly other glycolytic enzymes may provide a target for enhanced therapeutic responsiveness thereby improving prognosis of patients with GBMs.

Anaesthesia for endovascular management of cerebral aneurysms

Subarachnoid haemorrhage due to rupture of cerebral aneurysms is a multisystem disease. Treatment of the condition in the past has relied on craniotomy and clipping of the aneurysm to prevent a recurrent haemorrhage. There is now emerging evidence to suggest that endovascular treatment of cerebral aneurysms may reduce the morbidity associated with open surgery. The anaesthetic management of interventional neuroradiology also creates new challenges due to the novel approach to treatment. Anaesthetists need to be familiar with this procedure and the management of potential complications. This review provides an overview such considerations.

An update of phase II results from RTOG 0211: A phase I/II study of gefitinib with radiotherapy in newly diagnosed glioblastoma

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Background: The epidermal growth factor receptor (EGFR) pathway is commonly deregulated in GBMs and its activity has been associated with treatment resistance in preclinical models. Accordingly, the Radiation Therapy Oncology Group (RTOG) recently conducted a Phase I/II study of Gefitinib, an EGFR tyrosine kinase inhibitor, in combination with radiotherapy for newly-diagnosed glioblastoma (GBM) patients. Methods: 178 GBM patients were entered on RTOG 0211 (Phase I: 31 patients and Phase II: 147 patients). The maximum tolerated dose (MTD) of Gefitinib was determined to be 500mg in non-EIACD patients, and the Phase II component of RTOG 0211 was continued at this dose level during radiation and as maintenance for 18 months afterward or until disease progression. Results: 119/147 patients completed treatment per protocol and/or with acceptable deviation. The median survival time for all patients in the study was 11.0 months. Progression-free survival was 5.1 months for all patients. When considering only patients who were treated per protocol, the median survival of RTOG 0211 patients was 11.5 months, compared to 11.0 months for historical controls treated in previous RTOG studies (p=0.14). RPA Class IV patients appeared to derive the greatest benefit from Gefitinib when combined with radiotherapy compared to historical controls, although not reaching statistical significance. Molecular and genetic profiling efforts are underway to determine which GBM patients derive greatest benefit from Gefitinib in the upfront setting, which will be reported at the time of the annual meeting. These include markers such as EGFRvIII and PTEN, which have been recently reported to be associated with response to anti-EGFR agents in the recurrent setting, and members of key signal transduction pathways regulated by EGFR. Conclusions: The observed survival advantage of newly-diagnosed GBM patients treated with Gefitinib in combination with radiotherapy compared to historical controls treated on previous RTOG studies does not reach statistical significance. Molecular and genetic profiling efforts are underway to identify subsets of GBM patients who might derive the greatest benefit from Gefitinib in the upfront setting.

No significant financial relationships to disclose.

The effect of vitamin A deficiency and dietary alpha-tocopherol on the stability of rat-liver lysosomes

1. Vitamin A-deficient rats and pair-fed controls were maintained on either normal or raised amounts of dietary alpha-tocopherol. 2. Their livers were fractionated and ;free' and ;total' lysosomal phosphatase were determined in the various fractions. The rate of release of this enzyme was determined in the mitochondria-lysosome-rich fraction during incubation at pH5 and 37 degrees . 3. The deficient livers showed increased enzymic activity. 4. Prolonged incubation caused more rapid enzyme release from the mitochondria-lysosome-rich fraction of the vitamin A-deficient rats receiving the normal amount of dietary alpha-tocopherol than from the equivalent fraction of their pair-fed controls receiving vitamin A. Raised dietary alpha-tocopherol reversed this phenomenon.

A randomised, crossover study of the Dorges, McCoy and Macintosh laryngoscope blades in a simulated difficult intubation scenario

The use of alternative adult laryngoscope blades in an unexpected difficult intubation was evaluated with a human patient simulator manikin. Twenty anaesthetists of varying experience attempted to intubate the trachea of a high fidelity simulator in both its normal and difficult intubation settings using Macintosh, Dorges and McCoy laryngoscopes in a randomised order. The time taken to intubate, Cormack and Lehane scores, percentage of glottic opening visible, failure rate, number of attempts and subjective ease of use were recorded. The Dorges and McCoy blades did not perform any better than the standard Macintosh blade in either the easy or difficult tracheal intubation settings. Guidelines recommending the use of an alternative blade in an unexpected difficult intubation scenario have limited supporting evidence. This study does not support this recommendation.