Permanent deterioration of fine motor skills after the resection of tumors in the supplementary motor area

Supplementary motor area syndrome (SMAS) represents a common neurosurgical sequela. The incidence and time frame of its occurrence have yet to be characterized after surgery for brain tumors. We examined patients suffering from a brain tumor preoperatively, postoperatively, and during follow-up examinations after three months, including fine motor skills testing and transcranial magnetic stimulation (TMS). 13 patients suffering from a tumor in the dorsal part of the superior frontal gyrus underwent preoperative, early postoperative, and 3-month follow-up testing of fine motor skills using the Jebsen-Taylor Hand Function Test (JHFT) and the Nine-Hole Peg Test (NHPT) consisting of 8 subtests for both upper extremities. They completed TMS for cortical motor function mapping. Test completion times (TCTs) were recorded and compared. No patient suffered from neurological deficits before surgery. On postoperative day one, we detected motor deficits in two patients, which remained clinically stable at a 3-month follow-up. Except for page-turning, every subtest indicated a significant worsening of function, reflected by longer TCTs (p < 0.05) in the postoperative examinations for the contralateral upper extremity (contralateral to the tumor manifestation). At 3-month follow-up examinations for the contralateral upper extremity, each subtest indicated significant worsening compared to the preoperative status despite improvement to the immediate postoperative level. We also detected significantly longer TCTs (p < 0.05) postoperatively in the ipsilateral upper extremity. This study suggests a long-term worsening of fine motor skills even three months after SMA tumor resection, indicating the necessity of targeted physical therapy for these patients.

Spectral and photophysical modifications of porphyrins attached to core-shell nanoparticles. Theory and experiment

Plasmonic nanostructures, of which gold nanoparticles are the most elementary example, owe their unique properties to localized surface plasmons (LSP), the modes of free electron oscillation. LSP alter significantly electromagnetic field in the nanostructure neighborhood (i.e., near-field), which can modify the electric dipole transition rates in organic emitters. This study aims at investigating the influence of Au@SiO₂core-shell nanoparticles on the photophysics of porphyrins covalently attached to the nanoparticles surface. Guided by theoretical predictions, three sets of gold nanoparticles of different sizes were coated with a silica layer of similar thickness. The outer silica surface was functionalized with either free-basemeso-tetraphenylporphyrin or its zinc complex. Absorption and emission bands of porphyrin overlap in energy with a gold nanoparticle LSP resonance that provides the field enhancement. Silica separates the emitters from the gold surface, while the gold core size tunes the energy of the LSP resonance. The signatures of weak-coupling regime have been observed. Apart from modified emission profiles and shortened S₁lifetimes, Q band part intensity of the excitation spectra significantly increased with respect to the Soret band. The results were explained using classical transfer matrix simulations and electronic states kinetics, taking into account the photophysical properties of each chromophore. The calculations could reasonably well predict and explain the experimental outcomes. The discrepancies between the two were discussed.

Non-Invasive Mapping for Effective Preoperative Guidance to Approach Highly Language-Eloquent Gliomas-A Large Scale Comparative Cohort Study Using a New Classification for Language Eloquence

Objective: A considerable number of gliomas require resection via direct electrical stimulation (DES) during awake craniotomy. Likewise, the feasibility of resecting language-eloquent gliomas purely based on navigated repetitive transcranial magnetic stimulation (nrTMS) has been shown. This study analyzes the outcomes after preoperative nrTMS-based and intraoperative DES-based glioma resection in a large cohort. Due to the necessity of making location comparable, a classification for language eloquence for gliomas is introduced. Methods: Between March 2015 and May 2019, we prospectively enrolled 100 consecutive cases that were resected based on preoperative nrTMS language mapping (nrTMS group), and 47 cases via intraoperative DES mapping during awake craniotomy (awake group) following a standardized clinical workflow. Outcome measures were determined preoperatively, 5 days after surgery, and 3 months after surgery. To make functional eloquence comparable, we developed a classification based on prior publications and clinical experience. Groups and classification scores were correlated with clinical outcomes. Results: The functional outcome did not differ between groups. Gross total resection was achieved in more cases in the nrTMS group (87%, vs. 72% in the awake group, p = 0.04). Nonetheless, the awake group showed significantly higher scores for eloquence than the nrTMS group (median 7 points; interquartile range 6-8 vs. 5 points; 3-6.75; p < 0.0001). Conclusion: Resecting language-eloquent gliomas purely based on nrTMS data is feasible in a high percentage of cases if the described clinical workflow is followed. Moreover, the proposed classification for language eloquence makes language-eloquent tumors comparable, as shown by its correlation with functional and radiological outcomes.

Paired-pulse navigated TMS is more effective than single-pulse navigated TMS for mapping upper extremity muscles in brain tumor patients

OBJECTIVE

Single-pulse navigated transcranial magnetic stimulation (sp-nTMS) is used for presurgical motor mapping in patients with motor-eloquent lesions. However, recently introduced paired-pulse nTMS (pp-nTMS) with biphasic pulses could improve motor mapping.

METHODS

Thirty-four patients (mean age: 56.0 ± 12.7 years, 53.0% high-grade glioma) with motor-eloquent lesions underwent motor mapping of upper extremity representations and nTMS-based tractography of the corticospinal tract (CST) by both sp-nTMS and pp-nTMS with biphasic pulses for the tumor-affected hemisphere before resection.

RESULTS

In three patients (8.8%), conventional sp-nTMS did not provide motor-positive points, in contrast to pp-nTMS that was capable of generating motor maps in all patients. Good concordance between pp-nTMS and sp-nTMS in the spatial location of motor hotspots and center of gravity (CoG) as well as for CST tracking was observed, with pp-nTMS leading to similar motor map volumes (585.0 ± 667.8 vs. 586.8 ± 204.2 mm³, p = 0.9889) with considerably lower resting motor thresholds (35.0 ± 8.8 vs. 32.8 ± 7.6% of stimulator output, p = 0.0004).

CONCLUSIONS

Pp-nTMS with biphasic pulses may provide motor maps even in highly demanding cases with tumor-affected motor structures or edema, using lower stimulation intensity compared to sp-nTMS.

SIGNIFICANCE

Pp-nTMS with biphasic pulses could replace standardly used sp-nTMS for motor mapping and may be safer due to lower stimulation intensity.

Setup presentation and clinical outcome analysis of treating highly language-eloquent gliomas via preoperative navigated transcranial magnetic stimulation and tractography

OBJECTIVE Awake surgery combined with intraoperative direct electrical stimulation (DES) and intraoperative neuromonitoring (IONM) is considered the gold standard for the resection of highly language-eloquent brain tumors. Different modalities, such as functional magnetic resonance imaging (fMRI) or magnetoencephalography (MEG), are commonly added as adjuncts for preoperative language mapping but have been shown to have relevant limitations. Thus, this study presents a novel multimodal setup consisting of preoperative navigated transcranial magnetic stimulation (nTMS) and nTMS-based diffusion tensor imaging fiber tracking (DTI FT) as an adjunct to awake surgery. METHODS Sixty consecutive patients (63.3% men, mean age 47.6 ± 13.3 years) suffering from highly language-eloquent left-hemispheric low- or high-grade glioma underwent preoperative nTMS language mapping and nTMS-based DTI FT, followed by awake surgery for tumor resection. Both nTMS language mapping and DTI FT data were available for resection planning and intraoperative guidance. Clinical outcome parameters, including craniotomy size, extent of resection (EOR), language deficits at different time points, Karnofsky Performance Scale (KPS) score, duration of surgery, and inpatient stay, were assessed. RESULTS According to postoperative evaluation, 28.3% of patients showed tumor residuals, whereas new surgery-related permanent language deficits occurred in 8.3% of patients. KPS scores remained unchanged (median preoperative score 90, median follow-up score 90). CONCLUSIONS This is the first study to present a clinical outcome analysis of this very modern approach, which is increasingly applied in neurooncological centers worldwide. Although human language function is a highly complex and dynamic cortico-subcortical network, the presented approach offers excellent functional and oncological outcomes in patients undergoing surgery of lesions affecting this network.

Study of tetraphenylporphyrins as modifiers of insulin amyloid aggregation

Amyloid fibrils are rigid β-pleated protein aggregates that are connected with series of harmful diseases and at the same time are promising as base for novel nanomaterials. Thus, design of compounds able to inhibit or redirect those aggregates formation is important both for the biomedical aims and for nanotechnology applications. Here, we studied the effect of tetraphenylporphyrins (metal free, their Cu and Pd complexes, and those functionalized by carboxy and amino groups on periphery) on insulin amyloid self-assembling. The strongest impact on insulin aggregation was demonstrated by a metal-free porphyrin bearing four carboxy groups. This compound strongly suppresses insulin aggregation (about 88% reduction in amyloid-sensitive probe emission) inducing formation of fibrils with the length close to this of free insulin (1.7 ± 0.6 μm as compared with 1.4 ± 0.4 μm, respectively) with an essentially reduced tendency to lateral aggregation. Contrarily, the presence of tetraphenylporphyrin containing four amino groups only slightly affects fibrils' morphology and makes weaker impact on insulin aggregation yield (about 44% reduction). This is explained by the ability of aromatic carboxy groups of 5,10,15,20-(tetra-4-carboxyphenyl)porphyrin to interact with complementary protein-binding groups and thus stabilize the supramolecular complex. For 5,10,15,20-(tetra-4-aminophenyl)porphyrin, full protonation takes place in acidic medium of protein aggregation reaction; this results in the high positive charge of TPPN4 (equal or close to +6) and hence higher contribution of coulombic repulsion to interaction of TPPN4 with insulin. One more possible mechanism of the lower inhibition effect of TPPN4 as compared with TPPC4 could be the more restricted possibility of the former as compared with the latter to form H bonds with insulin groups. It was also shown that metal-free, Pd-containing, and Cu-containing tetraphenylporphyrins without peripheral substituents make almost the same impact on the protein self-assembling. We suppose this to be due to coordination saturation of these metal atoms.

Quality-adjusted life years in glioma patients: a systematic review on currently available data and the lack of evidence-based utilities

BACKGROUND

Cost-effectiveness studies gain importance in the context of rising health care expenses and treatment options. Especially in the neuro-oncological context, surgical therapy may increase overall survival, but restrain the patient by postoperative disability. Quality-adjusted life years, express treatment effects and are based on health utilities. In our study, we analyze the current evidence on health economic evaluations in glioma patients.

MATERIAL AND METHODS

We performed a systematic database search including Medline and Cochrane Library. Studies were critically appraised for statistical analyzes including glioma patients, health economic modeling and detailed health outcome. Study evidence was classified according to levels of evidence for therapeutic studies from the Centre for Evidence-Based Medicine (Oxford).

RESULTS

37 studies (1995-2018) were identified, 29 matched our inclusion criteria. Studies addressed surgical cost-efficiency and/or the standard treatment, postoperative chemotherapy (n = 6) and 5-ALA (n = 3). Only 16 studies used QALY as the outcome measure, most used overall survival or life years gained (LYG). Utilities were either based on one single study (Garside et al. in Health Technol Assess 11:iii-iv, ix-221) or derived from visual analogue scale (VAS). None assessed quality of life values for specific health statuses or utilities. Incremental cost-effectiveness ratios varied from 8325€ per QALY (5-ALA) to 518,342€ per LYG (tumor treating fields).

CONCLUSIONS

Only one study generated utility values to conduct cost-effectiveness analysis (CEA); most studies used indirect outcomes such as LYG or based their model on previously published data. Health economic evaluations lack specific utilities, further investigations are necessary to conduct reliable CEA in the neurosurgical context.

Functional Reorganization of Cortical Language Function in Glioma Patients-A Preliminary Study

Background: Functional reorganization (FR) was shown in glioma patients by direct electrical stimulation (DES) during awake craniotomy. This option for repeated mapping is available in cases of tumor recurrence and after decision for a second surgery. Navigated repetitive transcranial magnetic stimulation (nrTMS) has shown a high correlation with results of DES during awake craniotomy for language-negative sites (LNS) and allows for a non-invasive evaluation of language function. This preliminary study aims to examine FR in glioma patients by nrTMS.

Methods: A cohort of eighteen patients with left-sided perisylvian gliomas underwent preoperative nrTMS language mapping twice. The mean time between mappings was 17 ± 12 months. The cortex was separated into anterior and posterior language-eloquent regions. We defined a tumor area and an area without tumor (WOT). Error rates (ER = number of errors per number of stimulations) and hemispheric dominance ratios (HDR) were calculated as the quotient of the left- and right-sided ER.

Results: In cases in which most language function was located near the tumor during the first mapping, we found significantly more LNS in the tumor area during the second mapping as compared to cases in which function was not located near the tumor (p = 0.049). Patients with seizures showed fewer LNS during the second mapping. We found more changes of cortical language function in patients with a follow-up time of more than 13 months and lower WHO-graded tumors.

Conclusion: Present results confirm that nrTMS can show FR of LNS in glioma patients. Its extent, clinical impact and correlation with DES requires further evaluation but could have a considerable impact in neuro-oncology.

Language-Eloquent White Matter Pathway Tractography and the Course of Language Function in Glioma Patients

Object: As various recent studies show, damage to white matter pathways leads to permanent functional deficits in a high percentage of patients. Particularly the subcortical language network is complex, and its visualization has a tremendous relevance for neurosurgeons. This pilot study aims to correlate language-eloquent white matter pathways with the course of language function after the resection of left-sided perisylvian gliomas.

Methods: We included 10 patients who underwent resection of highly language-eloquent high- (9 pts) and low-grade gliomas (1 pts). We performed navigated repetitive transcranial magnetic stimulation (nrTMS)-based tractography via diffusion tensor imaging fiber trackings (DTI FT) preoperatively (PRE-1), postoperatively (POST-1), and at long-term follow up or tumor recurrence (PRE-2). We separately tracked the inferior fronto-occipital fascicle (IFOF), the frontal aslant tract (FAT), and the superior longitudinal (SLF), and arcuate fascicle (AF), and correlated the amount of visualized fibers to the patients' language function at each date.

Results: The changes of nrTMS-based DTI FTs of single white matter pathways correlated with the according status of language function for any of the pathways in 80% of patients and in 19 of 30 (63%) single pathway comparisons between PRE-1 and POST-1. Between POST-1 and PRE-2 the nrTMS-based DTI FTs correlated with the status of language function for any of the pathways in all patients and in 24 of 30 (80%) single pathway comparisons. Single FT results correlated with the according status of language function at POST-1 in 60, 70, and 60% of cases, and with the according status of language function at PRE-2 in 60, 90, and 90% of cases for the tracking of the IFOF, FAT, and SLF/AF, respectively.

Conclusion: By the present results we were able to show that nrTMS-based DTI FT of the IFOF, FAT, and SLF/AF mainly correlates with the according status of language function preoperatively, postoperatively, and at long-term follow up after the resection of left-sided perisylvian gliomas.

Two Macrocycles in One Shot: Synthesis, Spectroscopy, Photophysics, and Tautomerism of 23-Oxahemiporphycene and 21-Oxacorrole-5-carbaldehyde

The synthesis of 23-oxahemiporphycene, the first monooxa analogue of hemiporphycene, a structural isomer of porphyrin, is reported. Its generation under McMurry reaction conditions is surprisingly accompanied by the appearance of a formyl derivative of oxacorrole, 21-oxacorrole-5-carbaldehyde. A mechanism for the formation of the latter is proposed, relying on pinacol rearrangement of titanium pinacolate. The structures of the most stable tautomeric forms are established for both compounds based on IR and NMR spectra combined with DFT calculations. Spectral and photophysical characteristics are compared with those of structurally similar macrocycles. Replacement of one nitrogen by oxygen in hemiporphycene has only a minor impact. In contrast, for corrole it leads to the enhancement of stability and to strongly reduced rates of nonradiative deactivation of the lowest excited singlet state. This is explained by the planarity of oxacorroles, achieved by removing one of the inner hydrogen atoms from the inner cavity. Unusual crystal packing is observed for the protonated form of 23-oxahemiporphycene, which exhibits a π-π stacked columnar alignment of positively charged macrocycle units.

Predicting brain tumor regrowth in relation to motor areas by functional brain mapping

Background

Due to frequent recurrences, high-grade gliomas still confer a poor prognosis. Several regrowth prediction models have been developed, but most of these models are based on cellular models or dynamic mathematical calculations, thus limiting direct clinical use. The present study aims to evaluate whether navigated transcranial magnetic stimulation (nTMS) or functional magnetic resonance imaging (fMRI) may be used to predict the direction of tumor regrowth.

Methods

Sixty consecutive patients with high-grade gliomas were enrolled prospectively and analyzed in a case-control design after tumor recurrence. All patients underwent serial MRI after surgery and suffered from recurrent tumors during a mean follow-up of 13.2 ± 14.9 months. Tumor regrowth speed and direction were measured in relation to motor areas defined by nTMS, nTMS-based tractography, and fMRI. Depending on initial resection, patients were separated into three groups (group 1: without residual tumor, group 2: residual tumor away from motor areas, and group 3: residual tumor facing motor areas).

Results

Sixty-nine percent of patients in group 1, 64.3% in group 2, and 66.7% in group 3 showed tumor recurrence towards motor eloquence on contrast-enhanced T1-weighted sequences (P = .9527). Average growth towards motor areas on contrast-enhanced T1-weighted sequences was 0.6 ± 1.5 (group 1), 0.6 ± 2.4 (group 2), and 2.3 ± 5.5 (group 3) mm/month (P = .0492).

Conclusion

This study suggests a new strategy to predict tumor regrowth patterns in high-grade glioma patients. Our approach could be directly applied in the clinical setting, thus having clinical impact on both surgical treatment and radiotherapy planning.

Ethics Committee Registration Number

2793/10.

Resection of Gliomas with and without Neuropsychological Support during Awake Craniotomy-Effects on Surgery and Clinical Outcome

Background

During awake craniotomy for tumor resection, a neuropsychologist (NP) is regarded as a highly valuable partner for neurosurgeons. However, some centers do not routinely involve an NP, and data to support the high influence of the NP on the perioperative course of patients are mostly lacking.

Objective

The aim of this study was to investigate whether there is a difference in clinical outcomes between patients who underwent awake craniotomy with and without the attendance of an NP.

Methods

Our analysis included 61 patients, all operated on for resection of a presumably language-eloquent glioma during an awake procedure. Of these 61 cases, 47 surgeries were done with neuropsychological support (NP group), whereas 14 surgeries were performed without an NP (non-NP group) due to a language barrier between the NP and the patient. For these patients, neuropsychological assessment was provided by a bilingual resident.

Results

Both groups were highly comparable regarding age, gender, preoperative language function, and tumor grades (glioma WHO grades 1–4). Gross total resection (GTR) was achieved more frequently in the NP group (NP vs. non-NP: 61.7 vs. 28.6%, P = 0.04), which also had shorter durations of surgery (NP vs. non-NP: 240.7 ± 45.7 vs. 286.6 ± 54.8 min, P < 0.01). Furthermore, the rate of unexpected tumor residuals (estimation of the intraoperative extent of resection vs. postoperative imaging) was lower in the NP group (NP vs. non-NP: 19.1 vs. 42.9%, P = 0.09), but no difference was observed in terms of permanent surgery-related language deterioration (NP vs. non-NP: 6.4 vs. 14.3%, P = 0.48).

Conclusion

We need professional neuropsychological evaluation during awake craniotomies for removal of presumably language-eloquent gliomas. Although these procedures are routinely carried out with an NP, this is one of the first studies to provide data supporting the NP’s crucial role. Despite the small group size, our study shows statistically significant results, with higher rates of GTR and shorter durations of surgery among patients of the NP group. Moreover, our data emphasize the common problem of language barriers between the surgical and neuropsychological team and patients requiring awake tumor resection.

Associations between clinical outcome and navigated transcranial magnetic stimulation characteristics in patients with motor-eloquent brain lesions: a combined navigated transcranial magnetic stimulation-diffusion tensor imaging fiber tracking approach

OBJECTIVE Navigated transcranial magnetic stimulation (nTMS) and diffusion tensor imaging fiber tracking (DTI FT) based on nTMS data are increasingly used for preoperative planning and resection guidance in patients suffering from motor-eloquent brain tumors. The present study explores whether nTMS-based DTI FT can also be used for individual preoperative risk assessment regarding surgery-related motor impairment. METHODS Data derived from preoperative nTMS motor mapping and subsequent nTMS-based tractography in 86 patients were analyzed. All patients suffered from high-grade glioma (HGG), low-grade glioma (LGG), or intracranial metastasis (MET). In this context, nTMS-based DTI FT of the corticospinal tract (CST) was performed at a range of fractional anisotropy (FA) levels based on an individualized FA threshold ([FAT]; tracking with 50%, 75%, and 100% FAT), which was defined as the highest FA value allowing for visualization of fibers (100% FAT). Minimum lesion-to-CST distances were measured, and fiber numbers of the reconstructed CST were assessed. These data were then correlated with the preoperative, postoperative, and follow-up status of motor function and the resting motor threshold (rMT). RESULTS At certain FA levels, a statistically significant difference in lesion-to-CST distances was observed between patients with HGG who had no impairment and those who developed surgery-related transient or permanent motor deficits (75% FAT: p = 0.0149; 100% FAT: p = 0.0233). In this context, no patient with a lesion-to-CST distance ≥ 12 mm suffered from any new surgery-related permanent paresis (50% FAT and 75% FAT). Furthermore, comparatively strong negative correlations were observed between the rMT and lesion-to-CST distances of patients with surgery-related transient paresis (Spearman correlation coefficient [r_s]; 50% FAT: r_s = -0.8660; 75% FAT: r_s = -0.8660) or surgery-related permanent paresis (50% FAT: r_s = -0.7656; 75% FAT: r_s = -0.6763). CONCLUSIONS This is one of the first studies to show a direct correlation between imaging, clinical status, and neurophysiological markers for the integrity of the motor system in patients with brain tumors. The findings suggest that nTMS-based DTI FT might be suitable for individual risk assessment in patients with HGG, in addition to being a surgery-planning tool. Importantly, necessary data for risk assessment were obtained without significant additional efforts, making this approach potentially valuable for direct clinical use.

Non-invasive Mapping of Face Processing by Navigated Transcranial Magnetic Stimulation

Background: Besides motor and language function, tumor resections within the frontal and parietal lobe have also been reported to cause neuropsychological impairment like prosopagnosia.

Objective: Since non-navigated transcranial magnetic stimulation (TMS) has previously been used to map neuropsychological cortical function, this study aims to evaluate the feasibility and spatial discrimination of repetitive navigated TMS (rTMS) mapping for detection of face processing impairment in healthy volunteers. The study was also designed to establish this examination for preoperative mapping in brain tumor patients.

Methods: Twenty healthy and purely right-handed volunteers (11 female, 9 male) underwent rTMS mapping for cortical face processing function using 5 Hz/10 pulses. Both hemispheres were investigated randomly with an interval of 2 weeks between mapping sessions. Fifty-two predetermined cortical spots of the whole hemispheres were mapped after baseline measurement. The task consisted of 80 portraits of popular persons, which had to be named while rTMS was applied.

Results: In 80% of all subjects rTMS elicited naming errors in the right middle middle frontal gyrus (mMFG). Concerning anomia errors, the highest error rate (35%) was achieved in the bilateral triangular inferior frontal gyrus (trIFG). With regard to similarly or wrongly named persons, we observed 10% error rates mainly in the bilateral frontal lobes.

Conclusion: It seems feasible to map the cortical face processing function and to generate face processing impairment via rTMS. The observed localizations are well in accordance with the contemporary literature, and the mapping did not interfere with rTMS-induced language impairment. The clinical usefulness of preoperative mapping has to be evaluated subsequently.

Intraoperative PEEP-ventilation during PMMA-injection for augmented pedicle screws: improvement of leakage rate in spinal surgery

BACKGROUND

Within the last two decades the use of polymethylmethacrylate (PMMA) in the treatment of osteoporotic vertebral fractures has been established widely. Several techniques of cement application in spinal surgery have been described. Besides classical vertebroplasty, kyphoplasty and related techniques that reinforce stability of the fractured vertebral body itself, augmentation of pedicle screws became an issue in the past 10 years. Aim of this technique is strengthening of the implant-bone-interface and the prevention of loosening and failure of posterior instrumentation in limited bone quality due to osteoporosis. PMMA use in spinal surgery always bears the risk of cement leakage and cement embolism. There are only few publications dealing with cement leakage in pedicle screw augmentation. We examined our cohort concerning incidence and type of leakage in comparison to the literature. In particular, we evaluated a possible role of intrathoracic pressure during cementation procedure.

PATIENTS AND METHODS

In this retrospective study 42 patients were included. Mean age was 74 (57-89) years. 311 fenestrated, augmented screws were analyzed postoperatively concerning leakage and subsequent pulmonary embolism of cement particles. Overall, there was a leakage rate of 38.3 %, and 28.6 % of patients showed pulmonary embolism of PMMA. During surgery, patients were in part ventilated with a positive end-expiratory pressure (PEEP) of 15 cmH2O during cement injection. These individuals showed significantly less leakage locally as well as less PMMA-emboli in the pulmonary circulation in contrast to patients ventilated without increased PEEP.

CONCLUSION

PEEP elevation during administration of PMMA via fenestrated pedicle screws is reducing the leakage rate in spinal surgery. These beneficial effects warrant further evaluation in prospective studies.

[Pelvic injuries in childhood and adolescence: Retrospective analysis of 5-year data from a national trauma centre]

BACKGROUND

Pelvic fractures are uncommon injuries in paediatric trauma patients because of specific anatomical features. Due to the low incidence there is no standardized therapeutic algorithm.

MATERIAL AND METHODS

This retrospective review evaluates paediatric pelvic fractures of a Level I Trauma Centre over 5 years. In addition, we compared the data with adult pelvic fractures and reviewed the literature. A total of 37 pelvic fractures (≤16 years) were documented, with an incidence of 9.9% in the child with multiple injuries. The most common injury mechanisms were traffic accidents, followed by falls from heights.

RESULTS

Type A injuries occurred in 50% (type B: 16%, type C: 27%, acetabular injuries: 11%). Osteosynthesis was performed in nine cases. Therapeutic intervention was necessary in three cases of haemodynamically relevant bleeding; 97% of all children had associated injuries (mean ISS: 38).

CONCLUSION

Our data showed some differences to the literature. Pelvic fractures are predictors for high injury severity. Despite similar fracture pattern, in contrast to adults most injuries could be treated non-operatively. In unstable or dislocated fractures open reduction and stabilization must be performed.

Single-walled carbon nanotube/lyotropic liquid crystal hybrid materials fabricated by a phase separation method in the presence of polyelectrolyte

We present a detailed study on the incorporation of single-walled carbon nanotubes (SWNTs) into lyotropic liquid crystals (LLC) by phase separation in the presence of polyelectrolytes. Two cases were studied in this work: (i) incorporation of SWNTs into the LLC phase formed by an anionic surfactant sodium dodecyl sulfate (SDS) in the presence of an anionic polyelectrolyte poly(sodium styrenesulfonate) (PSS); (ii) incorporation of SWNTs into the LLC phase formed by a cationic surfactant cetyltrimethylammonium bromide (CTAB) in the presence of a cationic polyelectrolyte poly(diallydimethylammonium chloride) (PDADMAC). The SWNTs/LLC composites were characterized by polarized optical microscopy (POM) observations and small-angle X-ray scattering (SAXS) measurements. In both systems, the surfactant phase was condensed into a hexagonal lattice by the polyelectrolyte within the investigated concentration range. Several factors that can influence the property of SWNTs/LLC composite were examined, including concentration of surfactants and polyelectrolytes and temperature. Aggregated SWNTs were not observed, indicating that SWNTs were well dispersed in the LLC phases. SAXS measurements showed the lattice parameter of the host LLC phase changed upon varying the mixing ratio of polyelectrolyte to ionic surfactant. The SWNTs/LLC hybrids showed considerable stability against temperature rise in both systems, and desorption of surfactant from SWNTs was not observed at higher temperature.

The biosynthesis of 8-O-methylated sialic acids in the starfish Asterias rubens--isolation and characterisation of S-adenosyl-L-methionine:sialate-8-O-methyltransferase

The unusual, 8-O-methylated sialic acids have only been found in glycoconjugates of certain species of starfish. Using a detergent-solubilised extract of a particulate fraction from gonads of Asterias rubens, a specific methylation of endogenous and exogenous glycoconjugate-bound sialic acids was detected with [14C]-S-adenosyl-L-methionine ([14C]AdoMet) as the methyl donor. For this test, a filtration assay was developed using glutardialdehyde-fixed horse erythrocyte membranes as methyl acceptor. The enzyme catalysing this reaction, the sialate-8-O-methyltransferase, was purified 22000-fold in a yield of 13% by ion-exchange chromatography and two cycles of affinity chromatography on S-adenosyl-L-homocysteine-Sepharose. Upon SDS/PAGE under reducing conditions, the purified sialate-8-O-methyltransferase revealed two bands with apparent molecular masses of 58 kDa and 62 kDa. Since no evidence for the presence of subunits was found, the relationship between these two species is unknown. The enzyme was optimally active over a broad range of pH (7.4-8.3) and at 37 degrees C. After EDTA treatment, restoration of the activity depended, in contrast to most methyltransferases, on Mn2+ or Co2+, the latter to a lesser extent. Although both, free N-acetylneuraminic acid and N-glycoloylneuraminic acid were methylated, sialic acids alpha-glycosidically bound to a number of oligosaccharides and glycoproteins were better substrates. In the presence of 20 microM AdoMet, apparent Km values of 299 microM and 44 microM were found for N-acetylneuraminic acid and N-acetylneuraminyl alpha2,3-lactose, respectively. Using N-acetylneuraminyl alpha2,3-lactose as acceptor, an apparent Km of 7.1 microM was found for S-adenosyl-L-methionine. Therefore, the sialate-8-O-methyltransferase is the first enzyme known to modify both free and glycoconjugate-bound sialic acids.