Utility of diffusion tensor imaging studies linked to neuronavigation and other modalities in repeat hemispherotomy for intractable epilepsy

OBJECT Hemispherectomy for unilateral, medically refractory epilepsy is associated with excellent long-term seizure control. However, for patients with recurrent seizures following disconnection, workup and investigation can be challenging, and surgical options may be limited. Few studies have examined the role of repeat hemispherotomy in these patients. The authors hypothesized that residual fiber connections between the hemispheres could be the underlying cause of recurrent epilepsy in these patients. Diffusion tensor imaging (DTI) was used to test this hypothesis, and to target residual connections at reoperation using neuronavigation. METHODS The authors identified 8 patients with recurrent seizures following hemispherectomy who underwent surgery between 1995 and 2012. Prolonged video electroencephalography recordings documented persistent seizures arising from the affected hemisphere. In all patients, DTI demonstrated residual white matter association fibers connecting the hemispheres. A repeat craniotomy and neuronavigation-guided targeted disconnection of these residual fibers was performed. Engel class was used to determine outcome after surgery at a minimum of 2 years of follow-up. RESULTS Two patients underwent initial hemidecortication and 6 had periinsular hemispherotomy as their first procedures at a median age of 9.7 months. Initial pathologies included hemimegalencephaly (n = 4), multilobar cortical dysplasia (n = 3), and Rasmussen's encephalitis (n = 1). The mean duration of seizure freedom for the group after the initial procedure was 32.5 months (range 6-77 months). In all patients, DTI showed limited but definite residual connections between the 2 hemispheres, primarily across the rostrum/genu of the corpus callosum. The median age at reoperation was 6.8 years (range 1.3-14 years). The average time taken for reoperation was 3 hours (range 1.8-4.3 hours), with a mean blood loss of 150 ml (range 50-250 ml). One patient required a blood transfusion. Five patients are seizure free, and the remaining 3 patients are Engel Class II, with a minimum follow-up of 24 months for the group. CONCLUSIONS Repeat hemispherotomy is an option for consideration in patients with recurrent intractable epilepsy following failed surgery for catastrophic epilepsy. In conjunction with other modalities to establish seizure onset zones, advanced MRI and DTI sequences may be of value in identifying patients with residual connectivity between the affected and unaffected hemispheres. Targeted disconnection of these residual areas of connectivity using neuronavigation may result in improved seizure outcomes, with minimal and acceptable morbidity.

Prognostic value of medulloblastoma extent of resection after accounting for molecular subgroup: a retrospective integrated clinical and molecular analysis

Background

Incomplete surgical resection of medulloblastoma is controversially considered a marker of high-risk disease; driving aggressive surgical resections, “second-look” surgeries, and/or intensified chemoradiotherapy. All prior publications evaluating the clinical importance of extent of resection (EOR) failed to account for molecular subgroup. We analysed the prognostic value of EOR across 787 medulloblastoma samples in a subgroup-specific manner.

Methods

We retrospectively identified patients from Medulloblastoma Advanced Genomics International Consortium (MAGIC) centres with a histological diagnosis of medulloblastoma and complete extent of resection and survival data. Specimens were collected from 35 international institutions. Medulloblastoma subgroup affiliation was determined using nanoString gene expression profiling on frozen or formalin-fixed paraffin-embedded tissues. Extent of resection (EOR) based on post-operative imaging was classified as gross total (GTR), near total (NTR, <1·5cm²), or subtotal (STR, ≥ 1·5cm²). Overall survival (OS) and progression-free survival (PFS) multivariable analyses including subgroup, age, metastatic status, geographical location of therapy (North America/Australia vs world), and adjuvant therapy regimen were performed. The primary endpoint was the impact of surgical EOR by molecular subgroup and other clinical variables on OS and PFS.

Findings

787 medulloblastoma patients (86 WNT, 242 SHH, 163 Group 3, and 296 Group 4) were included in a multivariable Cox model of PFS and OS. The marked benefit of EOR in the overall cohort was greatly attenuated after including molecular subgroup in the multivariable analysis. There was an observed PFS benefit of GTR over STR (hazard ration [HR] 1·45, 95% CI; 1·07–1·96, p=0·02) but there was no observed PFS or OS benefit of GTR over NTR (HR 1·05, 0·71–1·53, p=0·82 and HR 1·14, 0·75–1·72, p=0.55). There was no statistically significant survival benefit to greater EOR for patients with WNT, SHH, or Group 3 patients (HR 1·03, 0·67–1·58, p=0·9 for STR vs. GTR). There was a PFS benefit for GTR over STR in patients with Group 4 medulloblastoma (HR1·97, 1·22–3·17, p=0·01), particularly those with metastatic disease (HR 2·22, 1–4·93, p=0·05). A nomogram based on this multivariable cox proportional hazards model shows the comparably smaller impact of EOR on relative risk for PFS and OS than subgroup affiliation, metastatic status, radiation dose, and adjuvant chemotherapy.

Interpretation

The prognostic benefit of EOR for patients with medulloblastoma is attenuated after accounting for molecular subgroup affiliation. Although maximal safe surgical resection should remain the standard of care, surgical removal of small residual portions of medulloblastoma is not recommended when the likelihood of neurological morbidity is high as there is no definitive benefit to GTR over NTR. Our results suggest a re-evaluation of the long-term implications of intensified craniospinal irradiation (36 Gy) in children with small residual portions of medulloblastoma.

Funding

Funding Canadian Cancer Society Research Institute, Terry Fox Research Institute, Canadian Institutes of Health Research, National Institutes of Health, Pediatric Brain Tumor Foundation, Garron Family Chair in Childhood Cancer Research.

Functional specialization of chordate CDK1 paralogs during oogenic meiosis

Cyclin-dependent kinases (CDKs) are central regulators of eukaryotic cell cycle progression. In contrast to interphase CDKs, the mitotic phase CDK1 is the only CDK capable of driving the entire cell cycle and it can do so from yeast to mammals. Interestingly, plants and the marine chordate, Oikopleura dioica, possess paralogs of the highly conserved CDK1 regulator. However, whereas in plants the 2 CDK1 paralogs replace interphase CDK functions, O. dioica has a full complement of interphase CDKs in addition to its 5 odCDK1 paralogs. Here we show specific sub-functionalization of odCDK1 paralogs during oogenesis. Differential spatiotemporal dynamics of the odCDK1a, d and e paralogs and the meiotic polo-like kinase 1 (Plk1) and aurora kinase determine the subset of meiotic nuclei in prophase I arrest that will seed growing oocytes and complete meiosis. Whereas we find odCDK1e to be non-essential, knockdown of the odCDK1a paralog resulted in the spawning of non-viable oocytes of reduced size. Knockdown of odCDK1d also resulted in the spawning of non-viable oocytes. In this case, the oocytes were of normal size, but were unable to extrude polar bodies upon exposure to sperm, because they were unable to resume meiosis from prophase I arrest, a classical function of the sole CDK1 during meiosis in other organisms. Thus, we reveal specific sub-functionalization of CDK1 paralogs, during the meiotic oogenic program.

Trans-splicing in metazoans: A link to translational control?

The trans-splicing of a spliced-leader RNA to a subset of mRNAs is a phenomenon that occurs in many species, including Caenorhabditis elegans, and yet the driving force for its evolution in disparate groups of animals remains unclear. Polycistronic mRNA resulting from the transcription of operons is resolved via trans-splicing, but operons comprise only a sub-set of trans-spliced genes. Using the marine chordate, Oikopleura dioica, we recently tested the hypothesis that metazoan operons accelerate recovery from growth arrest. We found no supporting evidence for this in O. dioica. Instead we found a striking relationship between trans-splicing and maternal mRNA in O. dioica, C. elegans and the ascidian, Ciona intestinalis. Furthermore, in O. dioica and C. elegans, we found evidence to suggest a role for mTOR signaling in the translational control of growth-related, trans-spliced maternal mRNAs. We propose that this may be a mechanism for adjusting egg number in response to nutrient levels in these species.

Co-expressed Cyclin D variants cooperate to regulate proliferation of germline nuclei in a syncytium

The role of the G1-phase Cyclin D-CDK 4/6 regulatory module in linking germline stem cell (GSC) proliferation to nutrition is evolutionarily variable. In invertebrate Drosophila and C. elegans GSC models, G1 is nearly absent and Cyclin E is expressed throughout the cell cycle, whereas vertebrate spermatogonial stem cells have a distinct G1 and Cyclin D1 plays an important role in GSC renewal. In the invertebrate, chordate, Oikopleura, where germline nuclei proliferate asynchronously in a syncytium, we show a distinct G1-phase in which 2 Cyclin D variants are co-expressed. Cyclin Dd, present in both somatic endocycling cells and the germline, localized to germline nuclei during G1 before declining at G1/S. Cyclin Db, restricted to the germline, remained cytoplasmic, co-localizing in foci with the Cyclin-dependent Kinase Inhibitor, CKIa. These foci showed a preferential spatial distribution adjacent to syncytial germline nuclei at G1/S. During nutrient-restricted growth arrest, upregulated CKIa accumulated in arrested somatic endoreduplicative nuclei but did not do so in germline nuclei. In the latter context, Cyclin Dd levels gradually decreased. In contrast, the Cyclin Dbβ splice variant, lacking the Rb-interaction domain and phosphodegron, was specifically upregulated and the number of cytoplasmic foci containing this variant increased. This upregulation was dependent on stress response MAPK p38 signaling. We conclude that under favorable conditions, Cyclin Dbβ-CDK6 sequesters CKIa in the cytoplasm to cooperate with Cyclin Dd-CDK6 in promoting germline nuclear proliferation. Under nutrient-restriction, this sequestration function is enhanced to permit continued, though reduced, cycling of the germline during somatic growth arrest.

Use of lumbar laminoplasty vs. laminotomy for transection of the filum terminale does not affect early complication rates or postoperative course

INTRODUCTION

Various techniques are used for spinal cord untethering. The purpose of this study was to compare patient characteristics, postoperative course, and early complications after laminotomy vs. laminoplasty for transection of the filum terminale for tethered cord release.

METHODS

Retrospective analysis of clinical and magnetic resonance imaging data was undertaken for all patients (<18 years) who underwent tethered cord release by transection of the filum terminale at Oregon Health & Science University, Doernbecher Children's Hospital, from 2000 to 2011.

RESULTS

Data from two hundred and forty-eight patients were analyzed. Mean age was 5.2 years (range 0.3 to 16.8 years). Access to the thecal space during surgery was achieved using laminotomy or laminoplasty in 82 (33.1 %) and 166 (66.9 %) patients, respectively. Laminoplasty patients were significantly younger than laminotomy patients (3.2 vs. 9.3 years, p<0.0001); other clinical and radiographic characteristics were similar between the groups. Nine patients (3.6 %) experienced early complications, including cerebrospinal fluid leak (n=2), suprafascial infection requiring surgical management and intravenous (IV) antibiotics (n=3) or IV antibiotics alone (n=1), a small area of peri-incisional cutaneous necrosis (n=1), perioperative seizures (n=1), and mild, transient malignant hyperthermia (n=1). There was no difference in the number of early complications between the two groups. Univariate and multivariate analyses revealed no significant risk factor for postoperative complication associated with technique. As judged by caregivers, independent of surgical technique, 97 % of patients improved after surgery.

CONCLUSION

There was no difference in complication risk when performing transection of the filum terminale for tethered cord release using laminotomy or laminoplasty.

Trans-splicing and operons in metazoans: translational control in maternally regulated development and recovery from growth arrest

Polycistronic mRNAs transcribed from operons are resolved via the trans-splicing of a spliced-leader (SL) RNA. Trans-splicing also occurs at monocistronic transcripts. The phlyogenetically sporadic appearance of trans-splicing and operons has made the driving force(s) for their evolution in metazoans unclear. Previous work has proposed that germline expression drives operon organization in Caenorhabditis elegans, and a recent hypothesis proposes that operons provide an evolutionary advantage via the conservation of transcriptional machinery during recovery from growth arrested states. Using a modified cap analysis of gene expression protocol we mapped sites of SL trans-splicing genome-wide in the marine chordate Oikopleura dioica. Tiled microarrays revealed the expression dynamics of trans-spliced genes across development and during recovery from growth arrest. Operons did not facilitate recovery from growth arrest in O. dioica. Instead, we found that trans-spliced transcripts were predominantly maternal. We then analyzed data from C. elegans and Ciona intestinalis and found that an enrichment of trans-splicing and operon gene expression in maternal mRNA is shared between all three species, suggesting that this may be a driving force for operon evolution in metazoans. Furthermore, we found that the majority of known terminal oligopyrimidine (TOP) mRNAs are trans-spliced in O. dioica and that the SL contains a TOP-like motif. This suggests that the SL in O. dioica confers nutrient-dependent translational control to trans-spliced mRNAs via the TOR-signaling pathway. We hypothesize that SL-trans-splicing provides an evolutionary advantage in species that depend on translational control for regulating early embryogenesis, growth and oocyte production in response to nutrient levels.

Using a 2-variable method in radionuclide shuntography to predict shunt patency

OBJECT

Radionuclide shuntography interpretation is uncertain when the tracer fails to enter the ventricles but quickly drains distally or when the tracer enters the ventricles but takes longer than 15 minutes to drain distally. The purpose of this study was to aid in the clinical interpretation of a variety of shuntography results and to determine the applicability of shuntography in different patient populations.

METHODS

The results of 259 shuntograms were reviewed. Chi-square analysis was performed to evaluate the relationship between clinical variables and shuntography results. Two-by-two binary classification analyses were performed to determine the sensitivity, specificity, positive predictive value, and negative predictive value for 4 different combinatorial types of shuntography results based on 2 variables: ventricular tracer entry and distal tracer drainage.

RESULTS

Median patient age was 19 years, and 51% of patients were male. The most common presentation in patients undergoing shuntography was headache (169/254, 66.5%) with radiographically stable ventricle size. Of 227 patients with available imaging data, 163 (71.8%) presented with the same ventricle size as shown on a previous asymptomatic scan, 43 (18.9%) had larger ventricles, and 21 (9.2%) had smaller ventricles. Within 30 days of shuntography, 74 of 259 patients (28.6%) underwent surgical shunt exploration: 65 were found to have an obstructed shunt and 9 were found to have a patent shunt. Of those patients not undergoing surgery, the median length of benign clinical follow-up was 1051 days. Clinical variables were not significantly associated with shuntography results, including valve type (p = 0.180), ventricle size (p = 0.556), age (p = 0.549), distal drainage site (p = 0.098), and hydrocephalus etiology (p = 0.937). Shuntography results of patients with myelomeningocele were not dissociable from those of the group as a whole. Sensitivity to diagnose shunt failure was lowest (37.5%) but specificity was highest (97.2%) when the definition of a "normal" shuntogram included any tracer movement into the distal site within 45 minutes. Conversely, sensitivity was highest (87.5%) and specificity was lowest (51.4%) when the definition was limited exclusively to tracer entry into the ventricles and distal drainage within 15 minutes.

CONCLUSIONS

Even with a stringent definition of a "normal" shuntogram, sensitivity and specificity were relatively low for a diagnostic test. Clinical variables such as valve type, ventricle size, patient age, distal drainage site, and etiology of hydrocephalus were not associated with shuntography results.

Results of a North American survey of rapid-sequence MRI utilization to evaluate cerebral ventricles in children

OBJECT

Growing concern about potential adverse effects of ionizing radiation exposure during imaging studies is particularly relevant to the pediatric population. To decrease radiation exposure, many institutions use rapid-sequence (or quick-brain) MRI to evaluate cerebral ventricle size. There are obstacles, however, to widespread implementation of this imaging modality. The purpose of this study was to define and quantify these obstacles to positively affect institutional and governmental policy.

METHODS

A 9-question survey was emailed to pediatric neurosurgeons who were either members or candidate members of the American Society of Pediatric Neurosurgeons at every one of 101 institutions in the US and Canada having such a neurosurgeon on staff. Responses were compiled and descriptive statistics were performed.

RESULTS

Fifty-six institutions completed the survey. Forty-four (79%) of the 56 institutions currently have a rapid-sequence MRI protocol to evaluate ventricle size, while 36 (64%) use it routinely. Of the 44 institutions with a rapid-sequence MRI protocol, 29 (66%) have had a rapid-sequence MRI protocol for less than 5 years while 39 (89%) have had a rapid-sequence MRI protocol for no more than 10 years. Thirty-six (88%) of 41 rapid-sequence MRI users responding to this question obtain a T2-weighted rapid-sequence MRI while 13 (32%) obtain a T1-weighted rapid-sequence MRI. Twenty-eight (64%) of 44 institutions never use sedation while an additional 12 (27%) rarely use sedation to obtain a rapid-sequence MRI (less than 5% of studies). Of the institutions with an established rapid-sequence MRI protocol, obstacles to routine use include lack of emergency access to MRI facilities in 18 (41%), lack of staffing of MRI facilities in 12 (27%), and the inability to reimburse a rapid-sequence MRI protocol in 6 (14%). In the 12 institutions without rapid-sequence MRI, obstacles to implementation include lack of emergency access to MRI facilities in 8 (67%), lack of staffing of MRI facilities in 7 (58%), the inability to reimburse in 3 (25%), and lack of administrative support in 3 (25%). To evaluate pediatric head trauma, 53 (96%) of 55 institutions responding to this question use noncontrast CT, no institution uses rapid-sequence MRI, and only 2 (4%) use standard MRI.

CONCLUSIONS

Many North American institutions have a rapid-sequence MRI protocol to evaluate ventricle size, with most developing this technique within the past 5 years. Most institutions never use sedation, and most obtain T2-weighted sequences. The greatest obstacles to the routine use of rapid-sequence MRI in institutions with and in those without a rapid-sequence MRI protocol are the lack of emergency access and staffing of the MRI facility during nights and weekends.

Spontaneous improvement in urological dysfunction in children with congenital spinal lipomas of the conus medullaris

Congenital spinal lipomas of the conus (SLCs) are among the most common closed neural tube defects. The treatment of SLC is an area of controversy because the true natural history of this condition is unknown. Here, the authors present two cases of SLC presenting in infancy with compromised lower urinary tract function, which was objectively confirmed by abnormal urodynamic studies. In both cases, there was spontaneous improvement in urodynamic parameters, with stable normal urinary function at the long-term follow-up. Although cases of spontaneous radiological regression of SLC have very infrequently been reported, they have not been associated with the reversal of already present neurological deficits. This report reinforces the need for further delineation of the true natural history of SLC and highlights the dynamic nature of associated neurological compromise over time.

Future climate scenarios for a coastal productive planktonic food web resulting in microplankton phenology changes and decreased trophic transfer efficiency

We studied the effects of future climate change scenarios on plankton communities of a Norwegian fjord using a mesocosm approach. After the spring bloom, natural plankton were enclosed and treated in duplicates with inorganic nutrients elevated to pre-bloom conditions (N, P, Si; eutrophication), lowering of 0.4 pH units (acidification), and rising 3°C temperature (warming). All nutrient-amended treatments resulted in phytoplankton blooms dominated by chain-forming diatoms, and reached 13–16 μg chlorophyll (chl) a l⁻¹. In the control mesocosms, chl a remained below 1 μg l⁻¹. Acidification and warming had contrasting effects on the phenology and bloom-dynamics of autotrophic and heterotrophic microplankton. Bacillariophyceae, prymnesiophyceae, cryptophyta, and Protoperidinium spp. peaked earlier at higher temperature and lower pH. Chlorophyta showed lower peak abundances with acidification, but higher peak abundances with increased temperature. The peak magnitude of autotrophic dinophyceae and ciliates was, on the other hand, lowered with combined warming and acidification. Over time, the plankton communities shifted from autotrophic phytoplankton blooms to a more heterotrophic system in all mesocosms, especially in the control unaltered mesocosms. The development of mass balance and proportion of heterotrophic/autotrophic biomass predict a shift towards a more autotrophic community and less-efficient food web transfer when temperature, nutrients and acidification are combined in a future climate-change scenario. We suggest that this result may be related to a lower food quality for microzooplankton under acidification and warming scenarios and to an increase of catabolic processes compared to anabolic ones at higher temperatures.

Clinical significance of imaging and histological characteristics of filum terminale in tethered cord syndrome

OBJECT

The pathophysiology of tethered cord syndrome (TCS) is uncertain; however, it has been suggested that fibrous and fatty elements within the filum terminale (FT) play a role. The objective of this study was to describe the radiological and histological features of the FT in TCS and determine if there are associations between those features and clinical outcomes, complications, and urodynamics.

METHODS

In this retrospective study, histological, MRI, and clinical data obtained in 293 patients with TCS who underwent FT transection were reviewed and analyzed in a multivariate analysis.

RESULTS

The median patient age was 4.9 years (range 0.3-64.3 years). On MRI, a fatty filum was present in 65% of patients and a thickened filum (> 2 mm) was seen in 45%. Histologically, the FT contained prominent fibrous tissue in 95%, nerve twigs in 79%, adipose tissue in 59%, and vascular tissue in 36%. Histological features associated with a thickened filum on MR images were adipose tissue (OR 3.5, p < 0.001), nerve twigs (OR 2.2, p = 0.028), and vascular tissue (OR 0.5, p = 0.025). Adipose tissue was associated with a conus level below the L2-3 disc space (OR 2.3, p = 0.031) and with a fatty filum on imaging (OR 9.8, p < 0.001). Nerve twigs were associated with abnormal urodynamics (OR 10.9, p = 0.049). The only variable predictive of clinical improvement was conus level; patients with conus levels caudal to L-2 were less likely to improve postoperatively (OR 0.3, p = 0.042).

CONCLUSIONS

Fibrous tissue was ubiquitous and may be important in the pathophysiology of TCS. Nerve twigs and adipose tissue were associated with abnormal urodynamics and low-lying coni, respectively. Although the majority of patients clinically improved, patients with normal conus levels had significantly better outcomes.

Characterization of the 18S rRNA gene for designing universal eukaryote specific primers

High throughput sequencing technology has great promise for biodiversity studies. However, an underlying assumption is that the primers used in these studies are universal for the prokaryotic or eukaryotic groups of interest. Full primer universality is difficult or impossible to achieve and studies using different primer sets make biodiversity comparisons problematic. The aim of this study was to design and optimize universal eukaryotic primers that could be used as a standard in future biodiversity studies. Using the alignment of all eukaryotic sequences from the publicly available SILVA database, we generated a full characterization of variable versus conserved regions in the 18S rRNA gene. All variable regions within this gene were analyzed and our results suggested that the V2, V4 and V9 regions were best suited for biodiversity assessments. Previously published universal eukaryotic primers as well as a number of self-designed primers were mapped to the alignment. Primer selection will depend on sequencing technology used, and this study focused on the 454 pyrosequencing GS FLX Titanium platform. The results generated a primer pair yielding theoretical matches to 80% of the eukaryotic and 0% of the prokaryotic sequences in the SILVA database. An empirical test of marine sediments using the AmpliconNoise pipeline for analysis of the high throughput sequencing data yielded amplification of sequences for 71% of all eukaryotic phyla with no isolation of prokaryotic sequences. To our knowledge this is the first characterization of the complete 18S rRNA gene using all eukaryotes present in the SILVA database, providing a robust test for universal eukaryotic primers. Since both in silico and empirical tests using high throughput sequencing retained high inclusion of eukaryotic phyla and exclusion of prokaryotes, we conclude that these primers are well suited for assessing eukaryote diversity, and can be used as a standard in biodiversity studies.

Percutaneous trigeminal tractotomy–nucleotomy with use of intraoperative computed tomography and general anesthesia: report of 2 cases

For confirming the correct location of the radiofrequency electrode before creation of a lesion, percutaneous CT-guided trigeminal tractotomy–nucleotomy is most commonly performed with the patient prone and awake. However, for patients whose facial pain and hypersensitivity are so severe that the patients are unable to rest their face on a support (as required with prone positioning), awake CT-guided tractotomy-nucleotomy might not be feasible. The authors describe 2 such patients, for whom percutaneous intraoperative CT-guided tractotomy-nucleotomy under general anesthesia was successful. One patient was a 79-year-old man with profound left facial postherpetic neuralgia, who was unable to tolerate awake CT-guided tractotomy-nucleotomy, and the other was a 45-year-old woman with intractable hemicranial pain that developed after a right frontal lesionectomy for epilepsy. Each patient underwent a percutaneous intraoperative CT-guided tractotomy-nucleotomy under general anesthesia. No complications occurred, and each patient reported excellent pain relief for up to 6 and 3 months after surgery, respectively. Percutaneous intraoperative CT-guided tractotomy-nucleotomy performed on anesthetized patients is effective for facial postherpetic neuralgia and postoperative hemicranial neuralgia.

Treatment with bevacizumab plus carboplatin for recurrent malignant glioma

OBJECTIVE

To estimate overall survival (OS), progression-free survival (PFS), imaging responses, and toxicities of bevacizumab plus carboplatin for the treatment of recurrent malignant glioma. The secondary objective was to estimate the agreement between postcontrast T1-weighted and T2-weighted magnetic resonance imaging.

METHODS

A retrospective analysis of 9 patients who received bevacizumab (10 mg/kg intravenously) and carboplatin (AUC 5 intravenously) for recurrent malignant glioma (World Health Organization grades III and IV) is presented. Eight of 9 patients received this regimen at first recurrence.

RESULTS

The median age and Karnofsky performance score were 51 years and 70, respectively. For the 5 patients with grade III gliomas, the median PFS was 126 days, whereas median OS was not attained at 517 days of follow-up. Six-month PFS was 40%, whereas 6-month OS was 60%. For the 4 patients with grade IV gliomas, the median PFS was 216 days, whereas the median OS was not attained at 482 days of follow-up. Six-month PFS was 50%, whereas 6-month OS was 75%. The agreement between contrast-enhanced T1-weighted and T2-weighted images to determine recurrence was moderate (kappa=0.5714). Three patients had grade 3 and 4 toxicities including hyponatremia and thrombocytopenia.

CONCLUSION

Patients who received the combination of bevacizumab plus carboplatin for recurrent malignant glioma had reasonable PFS, OS, and toxicities. The median OS in our series is promising at well over 1 year. Agreement between postcontrast T1- and T2-weighted images is only moderate in the context of bevacizumab therapy.

Abstract 3930: Analysis of longitudinal relaxation time mapping for monitoring vascular permeability in brain tumors

Introduction: Vessel permeability measurement in tumors, as assessed by Ktrans exchange coefficient, may have diagnostic value for determining treatment effectiveness and are an emerging parameter for drug transport modeling. Transvascular exchange models have been the standard for deriving Ktrans in an imaging voxel based on the pharmacokinetic analysis of the longitudinal relaxation time (T1) measurements following systemic delivery of T1-shortening contrast reagent (CR) in tissue using dynamic contrast-enhanced (DCE)-MRI. Analysis requires a pre-contrast longitudinal relaxation time (T10) as a model input. This study investigates the effect of using T10 maps versus an average value for analyzing changes in Ktrans measurements in intracerebral lung carcinoma, glioma, and melanoma xenograft models before and after treatment with agents targeting tumor edema.

Materials and Methods: Rats were inoculated in the right basal ganglia with LX-1 human lung carcinoma (n = 10), UW28 human glioma (n = 11), or A2058 human melanoma cells (n = 15). After baseline MRI scans, animals received glyburide (∼24 μg/kg oral), dexamethasone (∼1.8 mg/kg IV) or vehicle control. MRI study was performed using a horizontal bore 11.75 T magnet system. T10 in tumor tissue was measured using a spin-echo inversion recovery sequence. DCE-MRI was done with a fast-gradient-echo sequence. Ktrans was calculated by non-linear squared fitting to the T1 measurements; animal-specific arterial input functions were used. A Student's two-tailed, paired t-test was used to test statistical significance of change in Ktrans between using T10 maps versus ROI-based T10 value.

Results and Discussion: On pre-treatment MRI, 50% of lung and melanoma metastases showed standard deviation ≥10% the average T10 value. For UW28 tumors, standard deviation was &lt;10% of the average T10 for all animals. LX-1 metastases became more heterogeneous based on σ increase. Ktrans was assessed using an ROI-based average T10 value and T10 maps before and after treatment. T10 mapping reduced average Ktrans in over 88% of cases (including pre- and post- treatment). Change in Ktrans from T10 mapping did not change with treatment (p ≥ 0.07) and change in Ktrans resulting from treatment was not significantly affected by T10 mapping (p ≥ 0.09) the treatment groups. There was a trend towards significance observed with larger animal numbers.

Conclusions: LX-1 and A2058 metastases were more heterogeneous than the UW28 model based on standard deviation of T10 values within tumor. Using an ROI-based average T10 value was likely to overpredict average Ktrans values, but not likely to significantly affect treatment outcomes of study for these tumors and therapies despite tumor heterogeneity. Overpredicted Ktrans hot spots could have more consequences on hot spot analysis to monitor treatment outcome rather than average Ktrans.

Citation Format: Gregory L. Pishko, Eric M. Thompson, Edward A. Neuwelt. Analysis of longitudinal relaxation time mapping for monitoring vascular permeability in brain tumors. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3930. doi:10.1158/1538-7445.AM2013-3930

The effect of alpha-v integrin inhibition on the malignant characteristics of medulloblastoma

OBJECT

Hypoxia induces an aggressive phenotype in some brain tumors in part due to hypoxia-inducible factor-1α (HIF-1α) and integrin expression. The importance of hypoxia in medulloblastoma is unclear and the interaction of HIF-1α and c-Myc in medulloblastoma has not been explored. The objective of this study was to determine if hypoxia induces an aggressive phenotype in human medulloblastoma cells that constitutively express high (D283 Med) or low (DAOY) levels of c-Myc and to determine if blocking α(v) integrins with the monoclonal antibody intetumumab inhibits hypoxia-induced cellular stress responses.

METHODS

Cells were grown at 21% and 1% O(2) and in the presence or absence of intetumumab. Measures of malignancy evaluated included cell proliferation, cell migration, and expression of vascular endothelial growth factor (VEGF), α(v) integrins, HIF-1α, and c-Myc.

RESULTS

Both cell lines robustly expressed α(v) integrins. Hypoxic DAOY cells showed significantly increased proliferation compared with normoxic controls (p < 0.05), whereas D283 Med cells did not. Both cell lines exhibited a dose-dependent decrease in proliferation when treated with intetumumab (p < 0.05). Hypoxia did not increase DAOY migration, but intetumumab significantly inhibited migration at both oxygen conditions (p < 0.05). Intetumumab significantly decreased VEGF levels in DAOY cells at both oxygen conditions (p < 0.05) and in normoxic D283 cells (p < 0.01). Neither cell line demonstrated increased HIF-1α expression in response to hypoxia. However, hypoxic D283 Med cells grown in the presence of intetumumab demonstrated significantly decreased c-Myc expression (p < 0.05).

CONCLUSIONS

Hypoxia did not clearly induce a more aggressive phenotype in medulloblastoma cells. Despite this result, intetumumab decreased medulloblastoma cell proliferation and migration and variably decreased VEGF and c-Myc expression in hypoxic conditions. Targeting α(v) integrins represents a promising potential adjuvant modality in the treatment of medulloblastoma, particularly subtypes that metastasize and overexpress VEGF and c-Myc.

OikoBase: a genomics and developmental transcriptomics resource for the urochordate Oikopleura dioica

We report the development of OikoBase (http://oikoarrays.biology.uiowa.edu/Oiko/), a tiling array-based genome browser resource for Oikopleura dioica, a metazoan belonging to the urochordates, the closest extant group to vertebrates. OikoBase facilitates retrieval and mining of a variety of useful genomics information. First, it includes a genome browser which interrogates 1260 genomic sequence scaffolds and features gene, transcript and CDS annotation tracks. Second, we annotated gene models with gene ontology (GO) terms and InterPro domains which are directly accessible in the browser with links to their entries in the GO (http://www.geneontology.org/) and InterPro (http://www.ebi.ac.uk/interpro/) databases, and we provide transcript and peptide links for sequence downloads. Third, we introduce the transcriptomics of a comprehensive set of developmental stages of O. dioica at high resolution and provide downloadable gene expression data for all developmental stages. Fourth, we incorporate a BLAST tool to identify homologs of genes and proteins. Finally, we include a tutorial that describes how to use OikoBase as well as a link to detailed methods, explaining the data generation and analysis pipeline. OikoBase will provide a valuable resource for research in chordate development, genome evolution and plasticity and the molecular ecology of this important marine planktonic organism.

The deleterious effects of methamphetamine use on initial presentation and clinical outcomes in aneurysmal subarachnoid hemorrhage

Object

The objective of this study was to retrospectively look at methamphetamine (MA) use in patients with aneurysmal subarachnoid hemorrhage (SAH) to determine if MA use affects clinical presentation and outcomes after aneurysmal SAH.

Methods

A retrospective review of patients admitted to the Oregon Health & Science University neurosurgical service with aneurysmal SAH during the past 6 years was undertaken. Variables analyzed included MA use, age, sex, cigarette use, Hunt and Hess grade, Fisher grade, admission blood pressure, aneurysm characteristics, occurrence of vasospasm, hospital length of stay (LOS), cerebral infarction, aneurysm treatment, and Glasgow Outcome Scale (GOS) score. Data differences between MA users and nonusers were statistically analyzed using multivariate logistic regression analysis. A separate comparison with randomly selected age-matched nonuser controls was also performed.

Results

Twenty-eight (7%) of 374 patients with aneurysmal SAH were identified as MA users. Methamphetamine users were younger than nonusers (45.2 vs 55.9 years, respectively; p <0.001). Despite a younger age, MA users had significantly higher Hunt and Hess grades than nonusers (3.0 vs 2.5, respectively; p <0.020) and age-matched controls (3.0 vs 2.0, respectively; p <0.001). Earliest available mean arterial pressure was significantly higher in MA users (122.1 vs 109.7, respectively; p = 0.005) than all nonusers but not age-matched controls. Methamphetamine users had significantly higher vasospasm rates than nonusers (92.9% vs 71.1%, respectively; p = 0.008) but similar rates as age-matched controls (92.9% vs 89.3%, respectively; p = 0.500). Glasgow Outcome Scale score did not differ significantly between users and nonusers (3 vs 4, respectively; p = 0.170), but users had significantly lower GOS scores than age-matched controls (3 vs 5, respectively; p <0.001). There was no statistically significant difference in the LOS between users and nonusers (18 days vs 16 days, respectively; p = 0.431) or users and age-matched controls (18 days vs 14 days, respectively; p = 0.250). In the multivariate analysis, MA use (OR 3.777, p = 0.018), age (p <0.001), Fisher grade (p = 0.011), Hunt and Hess grade (p <0.001), and cerebral infarction (p <0.001) were predictors of poor GOS score. The only predictor of vasospasm was age (p <0.001), although a strong predictive trend in MA use (p = 0.149) was found. Predictors of a hospital LOS >15 days included age (p = 0.002), Fisher grade (p = 0.002), Hunt and Hess grade (p <0.001), and cerebral infarction (p <0.001). Predictors of cerebral infarction include male sex (p = 0.022) and Hunt and Hess grade (p = 0.006), with vasospasm demonstrating a strong trend (p = 0.056).

Conclusions

A history of MA use may predict poorer outcomes in patients who present with aneurysmal SAH. Methamphetamine users have significantly worse presentations and outcomes when compared with age-matched controls.

Optimal timing of autologous cranioplasty after decompressive craniectomy in children

OBJECT

The object of this study was to determine if early cranioplasty after decompressive craniectomy for elevated intracranial pressure in children reduces complications.

METHODS

Sixty-one consecutive cases involving pediatric patients who underwent autologous cranioplasty after decompressive craniectomy for raised intracranial pressure at a single academic children's hospital over 15 years were studied retrospectively.

RESULTS

Sixty-one patients were divided into early (< 6 weeks; 28 patients) and late (≥ 6 weeks; 33 patients) cranioplasty cohorts. The cohorts were similar except for slightly lower age in the early (8.03 years) than the late (10.8 years) cranioplasty cohort (p < 0.05). Bone resorption after cranioplasty was significantly more common in the late (42%) than the early (14%) cranioplasty cohort (p < 0.05; OR 5.4). No other complication differed in incidence between the cohorts.

CONCLUSIONS

After decompressive craniectomy for raised intracranial pressure in children, early (< 6 weeks) cranioplasty reduces the occurrence of reoperation for bone resorption, without altering the incidence of other complications.

Vagus nerve stimulation for partial and generalized epilepsy from infancy to adolescence

OBJECT

Vagus nerve stimulation (VNS) is approved by the FDA for the treatment of partial epilepsy in patients older than 12 years. Authors of the current study performed a large retrospective analysis and comparison of VNS outcomes in children with an age ≥ and < 12 years, including those with partial and generalized epilepsy.

METHODS

A retrospective review of the records of pediatric patients (age < 18 years) who had undergone primary VNS system implantation between 2001 and 2010 by a single pediatric neurosurgeon was undertaken. Considered data included demographics, epilepsy type (partial vs generalized), seizure frequency, seizure duration, postictal period duration, and antiepileptic medication use.

RESULTS

One hundred forty-six patients (49% female) were followed up for a mean of 41 months after VNS implantation. Thirty-two percent of patients had partial epilepsy and 68% had generalized epilepsy. After VNS system implantation, seizure frequency was reduced in 91% of patients, seizure duration in 50%, postictal period in 49%, and antiepileptic medication use in 75%. There was no significant difference in age, sex, or duration of follow-up according to epilepsy type. Neither was there any significant difference in seizure frequency reduction, seizure duration, postictal period, medication use, overall clinical improvement, or improvement in quality of life based on an age ≥ or < 12 years or epilepsy type.

CONCLUSIONS

Vagus nerve stimulation reduced both seizure frequency and antiepileptic medication use in the majority of pediatric patients regardless of sex, age cohort, or epilepsy type. Vagus nerve stimulation also reduced seizure duration and postictal period in approximately half of the pediatric patients. Contrary to expectation, children with partial epilepsy do not benefit from VNS at higher rates than those with generalized epilepsy.

The evolving proteome of a complex extracellular matrix, the Oikopleura house

Extracellular matrices regulate biological processes at the level of cells, tissues, and in some cases, entire multicellular organisms. The subphylum Urochordata exemplifies the latter case, where animals are partially or completely enclosed in “houses” or “tunics”. Despite this common strategy, we show that the house proteome of the appendicularian, Oikopleura, has very little in common with the proteome of the sister class, ascidian, Ciona. Of 80 identified house proteins (oikosins), ∼half lack domain modules or similarity to known proteins, suggesting de novo appearance in appendicularians. Gene duplication has been important in generating almost 1/3 of the current oikosin complement, with serial duplications up to 8 paralogs in one family. Expression pattern analyses revealed that individual oikosins are produced from specific fields of cells within the secretory epithelium, but in some cases, migrate up to at least 20 cell diameters in extracellular space to combine in defined house structures. Interestingly, peroxidasin and secretory phospholipase A₂ domains, implicated in innate immune defence are secreted from the anlage associated with the food-concentrating filter, suggesting that this extra-organismal structure may play, in part, such a role in Oikopleura. We also show that sulfation of proteoglycans is required for the hydration and inflation of pre-house rudiments into functional houses. Though correct proportioning in the production of oikosins would seem important in repetitive assembly of the complex house structure, the genomic organization of oikosin loci appears incompatible with common enhancers or locus control regions exerting such a coordinate regulatory role. Thus, though all tunicates employ extracellular matrices based on a cellulose scaffold as a defining feature of the subphylum, they have evolved radically different protein compositions associated with this common underlying structural theme.