Ulf Nestler

Counterbalancing risks and gains from extended resections in malignant glioma surgery: a supplemental analysis from the randomized 5-aminolevulinic acid glioma resection study. Clinical article.

OBJECT Accumulating data suggest more aggressive surgery in patients with malignant glioma to improve outcome. However, extended surgery may increase morbidity. The randomized Phase III 5-aminolevulinic acid (ALA) study investigated 5-ALA-induced fluorescence as a tool for improving resections. An interim analysis demonstrated more frequent complete resections with longer progression-free survival (PFS). However, marginal differences were found regarding neurological deterioration and the frequency of additional therapies. Presently, the authors focus on the latter aspects in the final study population, and attempt to determine how safety might be affected by cytoreductive surgery. METHODS Patients with malignant gliomas were randomized for fluorescence-guided (ALA group) or conventional white light (WL) (WL group) microsurgery. The final intent-to-treat population consisted of 176 patients in the ALA and 173 in the WL group. Primary efficacy variables were contrast-enhancing tumor on early MR imaging and 6-month PFS. Among secondary outcome measures, the National Institutes of Health Stroke Scale (NIH-SS) score and the Karnofsky Performance Scale (KPS) score were used for assessing neurological function. RESULTS More frequent complete resections and improved PFS were confirmed, with higher median residual tumor volumes in the WL group (0.5 vs 0 cm(3), p = 0.001). Patients in the ALA group had more frequent deterioration on the NIH-SS at 48 hours. Patients at risk were those with deficits unresponsive to steroids. No differences were found in the KPS score. Regarding outcome, a combined end point of risks and neurological deficits was attempted, which demonstrated results in patients in the ALA group to be superior to those in participants in the WL group. Interestingly, the cumulative incidence of repeat surgery was significantly reduced in ALA patients. When stratified by completeness of resection, patients with incomplete resections were quicker to deteriorate neurologically (p = 0.0036). CONCLUSIONS Extended resections performed using a tool such as 5-ALA-derived tumor fluorescence, carries the risk of temporary impairment of neurological function. However, risks are higher in patients with deficits unresponsive to steroids.

Temozolomide-Mediated Radiation Enhancement in Glioblastoma: A Report on Underlying Mechanisms

Purpose: In this study, we investigated the mechanisms by which temozolomide enhances radiation response in glioblastoma cells. Experimental Design: Using a panel of four primary human glioblastoma cell lines with heterogeneous O6-methylguanine-DNA methyltransferase (MGMT) protein expression, normal human astrocytes, and U87 xenografts, we investigated (a) the relationship of MGMT status with efficacy of temozolomide-based chemoradiation using a panel of in vitro and in vivo assays; (b) underlying mechanisms by which temozolomide enhances radiation effect in glioblastoma cells; and (c) strategies to overcome resistance to radiation + temozolomide. Results: Temozolomide enhances radiation response most effectively in glioblastomas without detectable MGMT expression. On concurrent radiation + temozolomide administration in MGMT-negative glioblastomas, there seems to be decreased double-strand DNA (dsDNA) repair capacity and enhanced dsDNA damage compared either with radiation alone or with sequentially administered temozolomide. Our data suggest that O6-benzylguanine can enhance the antitumor effects of concurrent radiation + temozolomide in MGMT-positive cells by enhancing apoptosis and the degree of dsDNA damage. O6-Benzylguanine was most effective when administered concurrently with radiation + temozolomide and had less of an effect when administered with temozolomide in the absence of radiation or when administered sequentially with radiation. Our in vivo data using U87 xenografts confirmed our in vitro findings. Conclusions: The present study shows that temozolomide enhances radiation response most effectively in MGMT-negative glioblastomas by increasing the degree of radiation-induced double-strand DNA damage. In MGMT-positive glioblastomas, depletion of MGMT by the addition of O6-benzylguanine significantly enhances the antitumor effect of concurrent radiation + temozolomide. These are among the first data showing mechanisms of synergy between radiation and temozolomide and the effect of MGMT.

Survivin enhances radiation resistance in primary human glioblastoma cells via caspase-independent mechanisms

The observed radioresistance of human glioblastoma multiforme (GBM) poses a major challenge, which, if overcome, may lead to significant advances in the management of this patient population. There is accumulating evidence from correlative studies that Survivin expression is associated with increased malignant potential of human gliomas. The purpose of this study was to investigate whether Survivin plays a direct role in mediating radiation resistance in primary human glioma cell lines, and, if so, investigating the underlying mechanisms. Our panel of GBM cell lines included two that were relatively radiation resistant (GM20 and GM21) and two that were more radiation sensitive (GM22 and GM23), which demonstrated differential levels of Survivin expression between the two groups. Through the use of adenoviral vectors containing either dominant-negative (pAd-S(T34A)) or wild-type Suvrivin (pAd-S(WT)), we were able to inactivate or overexpress Survivin, respectively. Our findings suggest that Survivin plays a critical role in mediating radiation resistance in primary GBM cells, in part through suppression of apoptotic cell death via a caspase-independent manner. We have identified novel mechanisms by which Survivin may enhance tumor cell survival upon radiation exposure such as regulation of double-strand DNA break repair and tumor cell metabolism, which were most evident in the radiation-resistant cell lines. These differences in Survivin function both in radiation-resistant vs radiation-sensitive cell lines and in the presence vs absence of radiation exposure warrant further investigation and highlight potentially important mechanisms of radiation resistance in these tumors.

Radiation enhances the invasive potential of primary glioblastoma cells via activation of the Rho signaling pathway.

SummaryGlioblastoma multiforme (GBM) is among the most treatment-refractory of all human tumors. Radiation is effective at prolonging survival of GBM patients; however, the vast majority of GBM patients demonstrate progression at or near the site of original treatment. We have identified primary GBM cell lines that demonstrate increased invasive potential upon radiation exposure. As this represents a novel mechanism by which radiation-treated GBMs can fail therapy, we further investigated the identity of downstream signaling molecules that enhance the invasive phenotype of irradiated GBMs. Matrigel matrices were used to compare the extent of invasion of irradiated vs. non-irradiated GBM cell lines UN3 and GM2. The in vitro invasive potential of these irradiated cells were characterized in the presence of both pharmacologic and dominant negative inhibitors of extracellular matrix and cell signaling molecules including MMP, uPA, IGFR, EGFR, PI-3K, AKT, and Rho kinase. The effect of radiation on the expression of these signaling molecules was determined with Western blot assays. Ultimately, the in vitro tumor invasion results were confirmed using an in vivo 9L GBM model in rats. Using the primary GBM cell lines UN3 and GM2, we found that radiation enhances the invasive potential of these cells via activation of EGFR and IGFR1. Our findings suggest that activation of Rho signaling via PI-3K is required for radiation-induced invasion, although not required for invasion under physiologic conditions. This report clearly demonstrates that radiation-mediated invasion is fundamentally distinct from invasion under normal cellular physiology and identifies potential therapeutic targets to overcome this phenomenon.

The combination of adenoviral HSV TK gene therapy and radiation is effective in athymic mouse glioblastoma xenografts without increasing toxic side effects

AbstractObject: In mouse models of prostate and breast cancer therapeutic effects are enhanced when adenoviral HSV TK gene therapy is combined with ionizing radiation. In the present study, we adopted this approach for the treatment of human glioblastoma xenografts in an athymic mouse model and assessed treatment results as well as toxic side effects. Methods: About 72 nude mice received intracerebral inoculations of 2 × 105 U87ΔEGFR cells. On day 7 after tumor implantation the study population was randomized into six treatment arms: (1) intratumoral buffer inoculation on day 7, (2) intratumoral adenoviral vector injection (2 × 109 vp) on day 7, (3) single dose radiation (2.1 Gy) on day 9, (4) adenoviral injection + radiation, (5) adenoviral injection + ganciclovir (GCV) (20 ug/g twice daily from day 8 to 17), (6) adenoviral injection + GCV + radiation. On day 21 half of the animals were sacrificed for histological evaluation of the brain tumors, the other half was assessed for survival. Results: This study showed significantly prolonged median survival time of 5 days for the GCV treated groups. The addition of radiation decreased the frequency of neurological symptoms and delayed the onset of deficits without altering the expression of thymidine kinase in the tumor cells. Conclusions: We conclude that adenoviral HSV TK gene therapy in combination with adjuvant radiotherapy does not generate increased toxic side effects in glioblastoma treatment. The prolonged survival time of animals receiving gene therapy and the reduced occurrence of neurological symptoms in irradiated mice constitute promising features of the combined treatment.

Idiopathic normal pressure hydrocephalus: diagnostic and predictive value of clinical testing, lumbar drainage, and CSF dynamics

OBJECTIVE The aim of the study was to analyze the diagnostic and predictive values of clinical tests, CSF dynamics, and intracranial pulsatility tests, compared with external lumbar drainage (ELD), for shunt response in patients with idiopathic normal pressure hydrocephalus (iNPH). METHODS Sixty-eight consecutive patients with suspected iNPH were prospectively evaluated. Preoperative assessment included clinical tests, overnight intracranial pressure (ICP) monitoring, lumbar infusion test (LIFT), and ELD for 24-72 hours. Simple and multiple linear regression analyses were conducted to identify predictive parameters concerning the outcome after shunt therapy. RESULTS Positive response to ELD correctly predicted improvement after CSF diversion in 87.9% of the patients. A Mini-Mental State Examination (MMSE) value below 21 was associated with nonresponse after shunt insertion (specificity 93%, sensitivity 67%). Resistance to outflow of CSF (ROut) > 12 mm Hg/ml/min was false negative in 21% of patients. Intracranial pulsatility parameters yielded different results in various parameters (correlation coefficient between pulse amplitude and ICP, slow wave amplitude, and mean ICP) but did not correlate to outcome. In multiple linear regression analysis, a calculation of presurgical MMSE versus the value after ELD, ROut, and ICP amplitude quotient during LIFT was significantly associated with outcome (p = 0.04). CONCLUSIONS Despite a multitude of invasive tests, presurgical clinical testing and response to ELD yielded the best prediction for improvement of symptoms following surgery. The complication rate of invasive testing was 5.4%. Multiple and simple linear regression analyses indicated that outcome can only be predicted by a combination of parameters, in accordance with a multifactorial pathogenesis of iNPH.

Adult long-term health-related quality of life of congenital hydrocephalus patients.

OBJECT Congenital hydrocephalus has a major impact on the lives of patients and their relatives, as well as their long-term neurological development and social integration. The aim of this study was to assess the self-reported health-related quality of life (HRQOL) of patients after reaching adulthood. METHODS A total of 31 patients who required CSF shunt treatment for congenital hydrocephalus within the 1st year of life (between 1963 and 1987) agreed to undergo a structured SF-36 self-assessment. An age-matched German standard cohort was used as control. Additional parameters of surgical, social, and global neurological outcome were analyzed. The mean patient age was 35 years (range 26-51 years, 13 females and 18 males). Hydrocephalus etiologies were posthemorrhagic hydrocephalus (n = 9), postinfectious hydrocephalus (n = 5), aqueductal stenosis (n = 10), myelomeningocele (n = 2), and unknown cause (n = 5). RESULTS The mean modified Rankin Scale score was 1.6 (range 0-4). Hydrocephalic patients achieved lower scores for the SF-36 items physical functioning (70.5 vs. 93.5, p < 0.05), physical role functioning (74.2 vs. 88.3, p < 0.05), and general health perceptions (64.5 vs. 72.3, p < 0.05). Emotional, social role functioning, and mental health items did not differ between the groups. Assessment of vitality and pain resulted in a trend to worse values. Whereas the Physical Component Summary score was lower (46.1 vs. 54.3, p < 0.05), the Mental Component Summary score was not significantly different (50.2 vs. 48.7, p = 0.3). There was neither a statistically significant difference between subgroups of different etiologies nor an association with the number of subsequent hydrocephalus-related surgeries. CONCLUSIONS Adult HRQOL for patients with congenital hydrocephalus appears to be similar to that for healthy con with regard to mental health and social functioning aspects. Physical impairment is a predominant factor of compro quality of life.

The Cerebral Surfactant System and Its Alteration in Hydrocephalic Conditions

Introduction Pulmonary Surfactant reduces surface tension in the terminal airways thus facilitating breathing and contributes to host’s innate immunity. Surfactant Proteins (SP) A, B, C and D were recently identified as inherent proteins of the CNS. Aim of the study was to investigate cerebrospinal fluid (CSF) SP levels in hydrocephalus patients compared to normal subjects. Patients and Methods CSF SP A-D levels were quantified using commercially available ELISA kits in 126 patients (0–84 years, mean 39 years). 60 patients without CNS pathologies served as a control group. Hydrocephalus patients were separated in aqueductal stenosis (AQS, n = 24), acute hydrocephalus without aqueductal stenosis (acute HC w/o AQS, n = 16) and idiopathic normal pressure hydrocephalus (NPH, n = 20). Furthermore, six patients with pseudotumor cerebri were investigated. Results SP A—D are present under physiological conditions in human CSF. SP-A is elevated in diseases accompanied by ventricular enlargement (AQS, acute HC w/o AQS) in a significant manner (0.67, 1.21 vs 0.38 ng/ml in control, p<0.001). SP-C is also elevated in hydrocephalic conditions (AQS, acute HC w/o AQS; 0.87, 1.71 vs. 0.48 ng/ml in controls, p<0.001) and in Pseudotumor cerebri (1.26 vs. 0.48 ng/ml in controls, p<0.01). SP-B and SP-D did not show significant alterations. Conclusion The present study confirms the presence of SPs in human CSF. There are significant changes of SP-A and SP-C levels in diseases affecting brain water circulation and elevation of intracranial pressure. Cause of the alterations, underlying regulatory mechanisms, as well as diagnostic and therapeutic consequences of cerebral SP’s requires further thorough investigations.

Localization, Occurrence, and CSF Changes of SP-G, a New Surface Active Protein with Assumable Immunoregulatory Functions in the CNS

Conventional surfactant proteins (A, B, C, and D) are important players of the innate immunity in the central nervous system and serve as effective regulators of cerebrospinal fluid rheology, probably being involved in clearance of detrimental metabolites like beta-amyloid and phospho-tau. Recently, a novel surfactant protein, SP-G, was described in kidneys and peripheral endocrine and exocrine glands. So far, its presence and possible functions in the central nervous system are unknown. Therefore, our study aimed to elucidate the presence of SP-G in the brain and its concentration in normal and pathologic samples of cerebrospinal fluid in order to gain first insight into its regulation and possible functions. A total of 121 samples of human cerebrospinal fluid (30 controls, 60 hydrocephalus patients, 7 central nervous system infections, and 24 brain hemorrhage patients) and 21 rat brains were included in our study. CSF samples were quantified using a commercially available ELISA system. Results were analyzed statistically using SPSS 22, performing Spearman Rho correlation and ANOVA with Dunnett’s post hoc analysis. Rat brains were investigated via immunofluorescence to determine SP-G presence and colocalization with common markers like aquaporin-4, glial fibrillary acidic protein, platelet endothelial adhesion molecule 1, and neuronal nuclear antigen. SP-G occurs associated with brain vessels, comparable to other conventional SPs, and is present in a set of cortical neurons. SP-G is furthermore actively produced by ependymal and choroid plexus epithelium and secreted into the cerebrospinal fluid. Its concentrations are low in control subjects and patients suffering from aqueductal stenosis, higher in normal pressure hydrocephalus (p < 0.01), and highest in infections of the central nervous system and brain hemorrhage (p < 0.001). Interestingly, SP-G did correlate with total CSF protein in patients with CNS infections and hemorrhage, but not with cell count. Based on the changes in CSF levels of SP-G in hydrocephalus, brain hemorrhage, and CNS infections as well as its abundance at CSF flow-related anatomical structures closely associated with immunological barrier systems, importance for CSF rheology, brain waste clearance, and host defense is assumable. Thus, SP-G is a potential new CSF biomarker, possibly not only reflecting aspects of CNS innate immune responses, but also rheo-dynamically relevant changes of CSF composition, associated with CSF malabsorbtion. However, further studies are warranted to validate our findings and increase insight into the physiological importance of SP-G in the CNS.

Traumatische Läsionen des Nervensystems

Polytrauma in children is rare but potentially life-threatening. At the site of the accident the physician has to stabilize respiration and circulation to achieve normoxia and normotonia. The Glasgow Coma Scale allows for assessment of the severity of the trauma and for an estimate of the prognosis. Accompanying lesions such as internal bleeding, spine fractures or peripheral nerve lesions have to be assessed. The patient will be transferred to a pediatric intensive care unit in a hospital with neurosurgical facilities. After eventual (neuro)surgical interventions, cerebral perfusion pressure has to be monitored and maintained. Early start of physiotherapy and supportive care involving parents and families enables a successful rehabilitation.