A high-density 3-dimensional culture model of human glioblastoma for rapid screening of therapeutic resistance.

Glioblastoma is among the most lethal cancers, with no known cure. A multitude of therapeutics are being developed or in clinical trials, but currently there are no ways to predict which patient may benefit the most from which drug. Assays that allow prediction of the tumor's response to anti-cancer drugs may improve clinical decision-making. Here, we present a high-density 3D primary cell culture model for short-term testing from resected glioblastoma tissue that is set up on the day of surgery, established within 7 days and viable for at least 3 weeks. High-density 3D cultures contain tumor and host cells, including microglia, and retain key histopathological characteristics of their parent tumors, including proliferative activity, expression of the marker GFAP, and presence of giant cells. This provides a proof-of-concept that 3D primary cultures may be useful to model tumor heterogeneity. Importantly, we show that high-density 3D cultures can be used to test chemotherapy response within a 2-3-week timeframe and are predictive of patient response to Temozolomide therapy. Thus, primary high-density 3D cultures could be a useful tool for brain cancer research and prediction of therapeutic resistance.

Disulfide HMGB1 acts via TLR2/4 receptors to reduce the numbers of oligodendrocyte progenitor cells after traumatic injury in vitro.

Traumatic brain injury (TBI) is associated with poor clinical outcomes; autopsy studies of TBI victims demonstrate significant oligodendrocyte progenitor cell (OPC) death post TBI; an observation, which may explain the lack of meaningful repair of injured axons. Whilst high-mobility group box-1 (HMGB1) and its key receptors TLR2/4 are identified as key initiators of neuroinflammation post-TBI, they have been identified as attractive targets for development of novel therapeutic approaches to improve post-TBI clinical outcomes. In this report we establish unequivocal evidence that HMGB1 released in vitro impairs OPC response to mechanical injury; an effect that is pharmacologically reversible. We show that needle scratch injury hyper-acutely induced microglial HMGB1 nucleus-to-cytoplasm translocation and subsequent release into culture medium. Application of injury-conditioned media resulted in significant decreases in OPC number through anti-proliferative effects. This effect was reversed by co-treatment with the TLR2/4 receptor antagonist BoxA. Furthermore, whilst injury conditioned medium drove OPCs towards an activated reactive morphology, this was also abolished after BoxA co-treatment. We conclude that HMGB1, through TLR2/4 dependant mechanisms, may be detrimental to OPC proliferation following injury in vitro, negatively affecting the potential for restoring a mature oligodendrocyte population, and subsequent axonal remyelination. Further study is required to assess how HMGB1-TLR signalling influences OPC maturation and myelination capacity.

Uncovering a Role for the Dorsal Hippocampal Commissure in Recognition Memory.

The dorsal hippocampal commissure (DHC) is a white matter tract that provides interhemispheric connections between temporal lobe brain regions. Despite the importance of these regions for learning and memory, there is scant evidence of a role for the DHC in successful memory performance. We used diffusion-weighted magnetic resonance imaging (DW-MRI) and white matter tractography to reconstruct the DHC in both humans (in vivo) and nonhuman primates (ex vivo). Across species, our findings demonstrate a close consistency between the known anatomy and tract reconstructions of the DHC. Anterograde tract-tracer techniques also highlighted the parahippocampal origins of DHC fibers in nonhuman primates. Finally, we derived diffusion tensor MRI metrics from the DHC in a large sample of human subjects to investigate whether interindividual variation in DHC microstructure is predictive of memory performance. The mean diffusivity of the DHC correlated with performance in a standardized recognition memory task, an effect that was not reproduced in a comparison commissure tract-the anterior commissure. These findings highlight a potential role for the DHC in recognition memory, and our tract reconstruction approach has the potential to generate further novel insights into the role of this previously understudied white matter tract in both health and disease.

GalR3 mediates galanin proliferative effects on postnatal hippocampal precursors.

Galanin, a neuropeptide co-released from noradrenergic and serotonergic projection neurons to the dentate gyrus, has recently emerged as an important mediator for signaling neuronal activity to the subgranular neurogenic stem cell niche supporting adult hippocampal neurogenesis. Galanin and its receptors appear to play key roles in depression-like behavior, and effects on hippocampal neurogenesis are relevant to pharmacological strategies for treating depression, which in part appear to rely on restoring altered neurogenesis. We previously demonstrated that the GalR2/3 receptor agonist Gal 2-11 is proliferative and proneurogenic for postnatal hippocampal progenitor cells; however, the specific receptor mediation remained to be identified. With the recent availability of M1145 (a specific GalR2 agonist), and SNAP 37889 (GalR3 specific antagonist), we extend our previous studies and show that while M1145 has no proliferative effect, the co-treatment of postnatal rat hippocampal progenitors with Gal 2-11 and SNAP 37889 completely abolished the Gal 2-11 proliferative effects. Taken together, these results clearly demonstrate that GalR3 and not GalR2 is the specific receptor subtype that mediates the proliferative effects of galanin on hippocampal progenitor cells. These results implicate GALR3 in the mediation of galanin neurogenic effects and, potentially, its neurogenic anti-depressant effects.

Neuropeptides and hippocampal neurogenesis.

Hippocampal neurogenesis is important for modulating the behavioural responses to stress and for certain forms of learning and memory. The mechanisms underlying the necessary coupling of neuronal activity to neural stem/progenitor cell (NSPC) function remain poorly understood. Within the dentate subgranular stem cell niche, local interneurons appear to play an important part in this excitation-neurogenesis coupling via GABAergic transmission, which promotes neuronal differentiation and integration. Neuropeptides such as neuropeptide Y (NPY), vasoactive intestinal peptide (VIP) and galanin have emerged as important mediators for signalling local and extrinsic interneuronal activity to subgranular zone precursors. Here we review the distribution of these neuropeptides and their receptors in the neurogenic area of the hippocampus and their precise effects on hippocampal neurogenesis. We also discuss neuropeptides' potential involvement in functional aspects of hippocampal neurogenesis particularly their involvement in the modulation of learning and memory and behavior responses.

Persistent and intractable ventriculitis due to retained ventricular catheters.

It is generally recommended that, in cases of difficulty in removing a ventricular catheter during a shunt revision, it is best left alone to avoid intraventricular haemorrhage. Retained ventricular catheters (RVCs) are usually safe, although in the presence of ventriculitis they may become colonized by organisms and become a source of persistent or recurrent infection. The authors present a case of persistent and intractable ventriculitis due to an old retained ventricular catheter. A 23-year-old female, who had a RVC and a functioning shunt, was admitted for a suspected blocked shunt. At surgery the shunt was found to be infected and external drainage was instituted. Over the next 4 months, she developed intractable and persistent staphylococcal ventriculitis, despite undergoing 10 further surgical procedures, and appropriate intravenous and intrathecal antibiotic therapy. She responded rapidly only after surgical removal of the old RVC via a craniotomy. The staphylococcus cultured from the RVC had an identical antibiogram to the organism responsible for the intractable ventriculitis. This case emphasizes the point that, although RVC are generally considered safe, removal becomes imperative in the presence of concurrent CSF infection that fails to respond quickly to intrathecal antibiotic therapy.

Seizure induced dentate neurogenesis does not diminish with age in rats.

Neurogenesis in the mammalian dentate gyrus occurs throughout life, is believed to be important for the laying down of episodic memory and diminishes significantly with increasing age. Pathological insults such as seizures, hypoxia and traumatic brain injury increase dentate neurogenesis compared to age matched controls. Using unilateral intracerebroventricular kainate we show that although baseline neurogenesis is significantly lower in 3 month old rats compared to 1 month old rats, kainate increases neurogenesis to reach similar levels in both age groups. Additionally, this effect is bilateral after a unilateral intracerebroventricular kainate injection. We conclude that the potential for dentate neurogenesis is maintained despite diminishing baseline levels with increasing age and that injury signals override the age related suppression of neurogenesis.

Chemopreventive agents: selenium.

The element selenium (Se) was recognized only 40 years ago as being essential in the nutrition of animals and humans. It is recognized as being an essential component of a number of enzymes, in which it is present as the amino acid selenocysteine. Se compounds have also been found to inhibit tumorigenesis in a variety of animal models, and recent studies indicate that supplemental Se in human diets may reduce cancer risk. The antitumorigenic activities have been associated with Se intakes that correct nutritionally deficient status in animals, as well as higher intakes that are substantially greater than those associated with maximal expression of the selenocysteine-containing enzymes. Therefore, it is proposed that while some cancer protection, particularly that involving antioxidant protection, involves selenoenzymes, specific Se metabolites, which are produced in significant amounts at relatively high Se intakes, also discharge antitumorigenic functions. According to this two-stage model of the roles of Se in cancer prevention, individuals with nutritionally adequate Se intakes may benefit from Se supplementation. Evidence for chemoprevention by Se and for the apparent mechanisms underlying these effects is reviewed to the end of facilitating the development of the potential of Se compounds as cancer chemopreventive agents.

Kainic acid increases the proliferation of granule cell progenitors in the dentate gyrus of the adult rat.

Granule cell progenitors in the dentate gyrus of the hippocampal formation have the unusual capacity to be able to divide in the brains of adult rats and primates. The basal proliferation rate of granule cell progenitors in the adult rat is low compared with development, however, it is possible that this rate may become significantly altered under pathological conditions such as epilepsy. We have investigated whether the proliferation of granule cell progenitors is increased in adult rats in a model of temporal lobe epilepsy, by using systemic bromodeoxyuridine injections to label dividing cells. We report here for the first time that granule cell neurogenesis is increased bilaterally 1 week after a single unilateral intracerebroventricular injection of kainic acid. Bromodeoxyuridine labeled neurons increased at least 6-fold on the side ipsilateral to the kainic acid injection compared to controls, but significantly, were also increased, by at least 3-fold on the side contralateral to the injection. The dividing cells in the subgranular zone were identified as neurons since they expressed Class III beta tubulin but not glial fibrillary acidic protein.

Report of a national neurosurgical emergency teleconsulting system.

OBJECTIVE: The goal was to develop a low-cost, national, neurosurgical emergency teleconsulting system that is independent of vendor computed tomographic (CT) or magnetic resonance imaging (MRI) scanner type. METHODS: Charge-coupled device scanners are used to digitize hard copies of CT and MRI scans. An enhanced optical density range is achieved by using an algorithm to fuse data from multiple exposures at different integration periods. The system is based on personal computers using Microsoft Windows 3.11. Data are transmitted on a wide-area network at 128 kilobits/s, over Integrated Systems Digital Network lines. The network connects both neurosurgical departments in Ireland to all major hospitals with CT/MRI scanners. RESULTS: The scanner optical density is 0.05 to 3.0, with 2.24 to 2.5 line pairs/mm. Five-megabyte images are transmitted uncompressed in 6 minutes. To date, more than 750 CT and MRI scans have been transmitted. The system is completely automated, and operator acceptance has been very high. Images are automatically stored and displayed at the receiving workstation, where the images can be viewed and manipulated on-screen. This system has significantly enhanced acute neurosurgical patient care. CONCLUSION: The system is cost effective and simple to use, has gained widespread physician acceptance, and delivers an image quality superior to that of many commercially available systems.

Motor nerve transplantation.

The motor nerve transplantation (MNT) technique is used to transfer an intact nerve into a denervated muscle by harvesting a neurovascular pedicle of muscle containing motor endplates from the motor endplate zone of a donor muscle and implanting it into a denervated muscle. Thirty-six adult New Zealand White rabbits underwent reinnervation of the left long peroneal (LP) muscle (fast twitch) with a motor nerve graft from the soleus muscle (slow twitch). The right LP muscle served as a control. Reinnervation was assessed using microstimulatory single-fiber electromyography (SFEMG), alterations in muscle fiber typing and grouping, and isometric response curves. Neurofilament antibody was used for axon staining. The neurofilament studies provided direct evidence of nerve growth from the motor nerve graft into the adjacent denervated muscle. Median motor endplate jitter was 13 microsec preoperatively, and 26 microsec at 2 months, 29.5 microsec at 4 months, and 14 microsec at 6 months postoperatively (p < 0.001). Isometric tetanic tension studies showed a progressive functional recovery in the reinnervated muscle over 6 months. There was no histological evidence of aberrant reinnervation from any source outside the nerve pedicle. Isometric twitch responses and adenosine triphosphatase studies confirmed the conversion of the reinnervated LP muscle to a slow-type muscle. Acetylcholinesterase studies confirmed the presence of functioning motor endplates beneath the insertion of the motor nerve graft. It is concluded that the MNT technique achieves motor reinnervation by growth of new nerve fibers across the pedicle graft into the recipient muscle.

Report of a national neurosurgical teleradiology system.

An emergency neurosurgical teleradiology system was initially installed in two referring hospitals in ireland to transmit images to the neurosurgical department in Cork. It was subsequently expanded to six major referring hospitals transmitting to both neurosurgical departments in ireland serving the entire population of 3.5 million people, effectively becoming a national teleradiology system. The system was based on PCs interconnected by leased data circuits and ISDN. The network was operational 24 hours a day. Over 750 emergency computerized tomography scans were transmitted and transmission failures occurred in only 6% of cases. We conclude that current PC technology can be used to form a peer-to-peer wide-area network upon which a robust emergency teleradiology system can be based.

A clinical study of parenchymal and subdural miniature strain-gauge transducers for monitoring intracranial pressure.

OBJECTIVE: Previous studies have shown that a new strain-gauge MicroSensor (Codman/Johnson & Johnson Professional, Inc., Randolph, MA) for measuring intracranial pressure (ICP) performs well in the intraventricular space. We hoped to evaluate the MicroSensor in the subdural space and the brain parenchyma, because ICP is often measured in these compartments when the ventricles are difficult to cannulate. METHODS: Fifteen patients had simultaneous recordings of ICP from an externally transduced fluid-filled subdural catheter, a MicroSensor placed within the subdural catheter, and a nearby MicroSensor placed intraparenchymally in the right frontal lobe. RESULTS: The total number of valid simultaneous recordings of ICP was 95,946. A highly significant correlation was found between the tissue MicroSensor ICP (TMICP) and the subdural MicroSensor ICP (SMICP) (n = 95,946; r = 0.89; P < 0.00005), the TMICP and the fluid-transduced subdural catheter ICP (r = 0.86, P < 0.00005), and the fluid-transduced subdural catheter ICP and SMICP (r = 0.88, P < 0.00005). The mean simultaneous difference between the TMICP and the SMICP was 0.1 +/- 3.8 mm Hg with no obvious bias. The fluid-transduced subdural catheter ICP was 2.8 +/- 3.9 mm Hg lower than the TMICP and 2.7 +/- 3.9 mm Hg lower than the SMICP (P < 0.0005). The mean zero drifts of the tissue and subdural MicroSensors were 0.312 and 0.475 mm Hg/d, respectively. The tissue MicroSensor recordings showed the best quality wave form with the least damping. CONCLUSION: The strain-gauge MicroSensor is highly accurate and stable in the tissue and subdural spaces.

Extradural haematoma in the Irish Republic: an analysis of 82 cases with emphasis on 'delay'.

Eighty-two cases of extradural haematoma were analysed to elucidate the factors contributing to delay in treatment and poor outcome. The majority of cases occurred in the first three decades of life with falls being the commonest aetiological factor. Five distinct modes of presentation are described. Excessive delay occurred in recognizing the condition and in subsequent transfer of patients. This resulted in many patients being operated on while in coma. Associated intracranial and extracranial injury occurred in a significant number of cases. Recommendations for the management of these patients are outlined.