A. Tommy Bergenheim

Genome-wide association study identifies five susceptibility loci for glioma.

To identify risk variants for glioma, we conducted a meta-analysis of two genome-wide association studies by genotyping 550K tagging SNPs in a total of 1,878 cases and 3,670 controls, with validation in three additional independent series totaling 2,545 cases and 2,953 controls. We identified five risk loci for glioma at 5p15.33 (rs2736100, TERT; P = 1.50 × 10−17), 8q24.21 (rs4295627, CCDC26; P = 2.34 × 10−18), 9p21.3 (rs4977756, CDKN2A-CDKN2B; P = 7.24 × 10−15), 20q13.33 (rs6010620, RTEL1; P = 2.52 × 10−12) and 11q23.3 (rs498872, PHLDB1; P = 1.07 × 10−8). These data show that common low-penetrance susceptibility alleles contribute to the risk of developing glioma and provide insight into disease causation of this primary brain tumor.

Epidermal growth factor receptor family (EGFR, ErbB2–4) in gliomas and meningiomas

Overexpression of epidermal growth factor receptor (EGFR, ErbB1) correlates with enhanced malignant potential of many human tumor types including glioblastoma multiforme. The significance of EGFR expression in meningiomas is, however, unclear. Reports regarding the other EGFR family members, ErbB2–4, in brain tumors are sparse. In this study, the expression of the EGFR family members was analyzed in relation to various parameters for the clinical importance of these receptors in 44 gliomas and 26 meningiomas. In gliomas, quantitative real-time reverse transcription (RT)-PCR revealed the highest EGFR mRNA expression in high-grade gliomas, while ErbB2 and ErbB3 mRNA were detected only in a few high-grade gliomas. In contrast, ErbB4 expression was most pronounced in low-grade gliomas. Immunohistochemistry showed significantly higher EGFR protein expression in high-grade gliomas compared to low-grade gliomas (P=0.004). ErbB2 protein expression was mainly seen in high-grade gliomas. ErbB3 protein expression was low in all gliomas analyzed. ErbB4 protein expression was significantly higher in low-grade gliomas than in high-grade gliomas (P=0.007). In meningiomas, quantitative real-time RT-PCR revealed expression of EGFR, ErbB2, and ErbB4 mRNA in the majority of the tumors. ErbB3 was detected in only one of the meningiomas analyzed. Immunohistochemistry demonstrated high ErbB2 protein expression in meningiomas. An intriguing observation in astrocytomas and oligodendrogliomas grade II, was a significantly decreased overall survival for patients with high EGFR protein expression (P=0.04). The high ErbB4 expression in low-grade compared to high-grade gliomas might suggest that ErbB4 acts as a suppressor of malignant transformation in brain tumors, which is in line with previous studies in other tumor types.

Baseline levels of glucose metabolites, glutamate and glycerol in malignant glioma assessed by stereotactic microdialysis.

The metabolism of high grade astrocytoma was studied in 15 patients using intra-tumoural microdialysis. Two catheters were implanted during a stereotactic biopsy procedure: one in the tumour and one in the peri-tumoural tissue. The patients were fully mobilized the same day as the operation. Microdialysis samples were collected the next day and subsequently analysed for glucose, lactate, pyruvate, glutamate and glycerol. The main objective was to establish base-line levels of the studied substances. In addition, an in vitro experiment was performed in order to estimate recovery for the flow rates and catheters used.Glucose showed a tendency to be lower in tumour than in peri-tumoural tissue, indicating a high energy demand of the tumour. Lactate was significantly higher in tumour tissue. This supports previous reports that high grade astrocytomas use glycolysis rather than respiration to meet their energy demand.The tumours were also classified into necrotic and non-necrotic, according to the radiological finding. The necrotic tumours showed significantly higher levels of glutamate. They also presented a tendency to higher levels of glycerol than the non-necrotic tumours. These findings might be explained by the release of intracellular glutamate and of cell-membrane glycerol by cell destruction.We believe that microdialysis in awake and mobilized patients will prove to be a valuable tool in investigating metabolic events in malignant brain tumours especially during therapy.

Boron neutron capture therapy (BNCT) for glioblastoma multiforme: A phase II study evaluating a prolonged high-dose of boronophenylalanine (BPA)

BACKGROUND AND PURPOSE To evaluate the efficacy and safety of boron neutron capture therapy (BNCT) for glioblastoma multiforme (GBM) using a novel protocol for the boronophenylalanine-fructose (BPA-F) infusion. PATIENT AND METHODS This phase II study included 30 patients, 26-69 years old, with a good performance status of which 27 have undergone debulking surgery. BPA-F (900 mg BPA/kg body weight) was given i.v. over 6h. Neutron irradiation started 2h after the completion of the infusion. Follow-up reports were monitored by an independent clinical research institute. RESULTS The boron-blood concentration during irradiation was 15.2-33.7 microg/g. The average weighted absorbed dose to normal brain was 3.2-6.1 Gy (W). The minimum dose to the tumour volume ranged from 15.4 to 54.3 Gy (W). Seven patients suffered from seizures, 8 from skin/mucous problem, 5 patients were stricken by thromboembolism and 4 from abdominal disturbances in close relation to BNCT. Four patients displayed 9 episodes of grade 3-4 events (WHO). At the time for follow-up, minimum ten months, 23 out of the 29 evaluable patients were dead. The median time from BNCT treatment to tumour progression was 5.8 months and the median survival time after BNCT was 14.2 months. Following progression, 13 patients were given temozolomide, two patients were re-irradiated, and two were re-operated. Patients treated with temozolomide lived considerably longer (17.7 vs. 11.6 months). The quality of life analysis demonstrated a progressive deterioration after BNCT. CONCLUSION Although, the efficacy of BNCT in the present protocol seems to be comparable with conventional radiotherapy and the treatment time is shorter, the observed side effects and the requirement of complex infrastructure and higher resources emphasize the need of further phase I and II studies, especially directed to improve the accumulation of (10)B in tumour cells.

Gender differences in disability and health-related quality of life in patients with Parkinson's disease treated with stereotactic surgery

Objectives – To investigate eventual differences between women and men with Parkinsons disease (PD) before and after surgery, with respect to clinical status, disability and health‐related quality of life (HRQoL).

Distribution of BPA and metabolic assessment in glioblastoma patients during BNCT treatment: a microdialysis study

Boron neutron capture therapy (BNCT) is dependent on the selective accumulation of boron-10 in tumour cells. To maximise the radiation effect, the neutrons should be delivered when the ratio between the boron concentration in tumour cells to that in normal tissues reaches maximum. However, the pharmacokinetics of p-boronophenylalanine (BPA) and other boron delivery agents are only partly known. We used microdialysis to investigate the extracellular in vivo kinetics of boron in three intracerebral compartments -- solid tumour, brain adjacent to tumour (BAT), and the normal brain, as well as the subcutaneous tissue before, during, and after BNCT treatment. The findings were compared to the pharmacokinetics of BPA in the blood. We also measured the glucose metabolism and the levels of glutamate and glycerol in those compartments. Four patients were studied, two patients underwent surgical tumour resection and in two a stereotactic biopsy was performed. The patients were given BPA (900 mg/kg body weight) by a 6--h infusion. The infusion was completed approximately 2--3 h before neutron irradiation. In tumour tissue the extracellular concentration of BPA followed that of blood with a maximal concentration of 31.2 ppm and a maximal ratio vs. blood of 1.07. In BAT, the maximal concentration of BPA was 18.0 ppm with the peak level delayed for 4--6 h compared to the peak in blood with a maximal ratio of 1.2. Maximal blood concentration found was 41.0 ppm. The uptake of BPA in the normal brain was considerably lower than that in the blood and tumour tissue. No change in glucose metabolism was observed. The extracellular level of glycerol was increased after treatment in tumour tissue but not in normal brain suggesting a selective acute cytotoxic effect of BNCT on tumour cells.

Technical Difficulties and Perioperative Complications of Retrogasserian Glycerol Rhizotomy for Trigeminal Neuralgia

In 139 patients, 260 consecutive retrogasserian glycerol rhizotomies for trigeminal neuralgia were retrospectively analyzed regarding technical surgical difficulties and immediate and early complications. Technical obstacles occurred in 47.3%. In 21 cases (8.1%), the surgical procedure had to be interrupted due to circumstances such as vasovagal reactions, cardiac arrest, or difficulties to find the trigeminal cistern. Complications or side effects, being either transient or persistent, occurred in 67.3%. In the vast majority, those unwanted effects were related to mild sensory deficits. However, in 28.1% the complications were other than mild affection of facial sensibility. These slightly graver complications included labial herpes (3.8%), anesthesia dolorosa (0.8%), moderate or severe affection of sensibility (18.8%), dysesthesia (22.7%), chemical meningitis (1.5%) and infectious meningitis (1.5%). In 5 patients (1.9%) hearing was affected. In one of them, this condition was also brought about by tinnitus, and in another patient a preexisting tinnitus deteriorated. Although the frequency of surgical difficulties was high, the success of the glycerol injection was hampered only in a minor number of procedures. The frequency of complications and side effects was high, but they were mostly mild due to their nature and non-disabling for the patient. However, long-lasting disabling side effects occurred, and this should not be neglected when informing patients preoperatively. The surgical training needed to perform the procedure is stressed, and the use of prophylactic antibiotics when accidentally penetrating the oral bucca is recommended. We consider retrogasserian glycerol rhizotomy to be a good surgical option for patients with trigeminal neuralgia not suitable for microvascular decompression and when pharmacological therapy is not sufficient or is not tolerated.

Expression of the proteolytic factors, tPA and uPA, PAI-1 and VEGF during malignant glioma progression

Various proteases and their inhibitors have been shown to be important in tumor invasion. Angiogenesis is further a prerequisite for the growth and progression of solid tumors. Since these systems are functionally linked, in situ hybridization and in situ zymography were used to investigate the spatial and temporal expression of factors representative of the plasmin/plasminogen system and of an angiogenic factor in the BT4C glioma model. This tumor is invasive with a high grade of neovascularization. Tissue‐type plasminogen activator urokinase‐type plasminogen activator and plasminogen activator inhibitor‐1 mRNA were expressed in glioma cells during the entire tumor growth. Early in the tumor development the expression was found throughout the small tumor (approximately 10 mm3) while later in the time course the expression was found predominantly in the invasive tumor border of the tumor. The in situ zymography demonstrated that the plasminogen activators were translated into functional proteins. Vascular endothelial growth factor mRNA was expressed following a similar spatial and temporal pattern with an early expression in the entire small tumor while later, in larger tumors, it was exclusively expressed in the invasive tumor edge. In normal brain, the ventricular ependyma, meningies, as well as scattered neurons expressed tissue‐type plasminogen activator mRNA. Vascular endothelial growth factor mRNA was observed in the choroid plexus, and in scattered cells in normal brain tissue. Our finding may suggest a functional co‐operation of tissue‐type plasminogen activator, urokinase‐type plasminogen activator, plasminogen activator inhibitor‐1 and vascular endothelial growth factor during glioma progression. This model could be of value when evaluating different treatment modalities aimed at blocking the migrating capacity and growth of glial tumors.

Spatial Expression of VEGF-A in Human Glioma

Astrocytoma, especially of high grade, is dependent on neovascularization for its growth and progression. The expression of vascular endothelial growth factor (VEGF-A), an important angiogenesis factor, has been demonstrated in perinecrotic cells in glioblastoma. In order to achieve more knowledge regarding the process of astrocytoma angiogenesis and growth we have investigated the expression of VEGF-A immunohistochemically in different areas of tumors.In 21 patients with astrocytomas of varying grade serial stereotactic biopsies were performed. Biopsies were taken from brain adjacent to tumor (BAT), tumor periphery, and tumor center. In the BAT region of high-grade astrocytomas, we found a frequent expression of VEGF-A in tumor cells and less frequent in blood vessels. In the periphery, there was an expression mainly in tumor cells while in the center of grade IV tumors VEGF-A was also frequently expressed in cells adjacent to necrosis. VEGF-A in astrocytoma grade II was demonstrated in viable tumor cells preferentially in the periphery but also in peripheral vessels and in centrally located tumor cells.The findings indicate that, in addition to hypoxia in necrotic areas there may be other factors that stimulate the expression of VEGF-A. It is suggested that VEGF-A may be a prerequisite for the aggressive and infiltrative growth of astrocytomas. Therefore, when operating high-grade astrocytomas it may be of importance to resect this aggressive peripheral part of the tumor and also to take this finding into account when planning radiotherapy.

Intracerebral microvascular measurements during deep brain stimulation implantation using laser Doppler perfusion monitoring.

The aim of the study was to investigate if laser Doppler perfusion monitoring (LDPM) can be used in order to differentiate between gray and white matter and to what extent microvascular perfusion can be recorded in the deep brain structures during stereotactic neurosurgery. An optical probe constructed to fit in the Leksell® Stereotactic System was used for measurements along the trajectory and in the targets (globus pallidus internus, subthalamic nucleus, zona incerta, thalamus) during the implantation of deep brain stimulation leads (n = 22). The total backscattered light intensity (TLI) reflecting the grayness of the tissue, and the microvascular perfusion were captured at 128 sites. Heartbeat-synchronized pulsations were found at all perfusion recordings. In 6 sites the perfusion was more than 6 times higher than the closest neighbor indicating a possible small vessel structure. TLI was significantly higher (p < 0.005) and the perfusion significantly lower (p < 0.005) in positions identified as white matter in the respective MRI batch. The measurements imply that LDPM has the potential to be used as an intracerebral guidance tool.