A practical guide for the preparation of C1-labeled α-amino acids using aldehyde catalysis with isotopically labeled CO2.

Isotopically carbon-labeled α-amino acids are valuable synthetic targets that are increasingly needed in pharmacology and medical imaging. Existing preparations rely on early stage introduction of the isotopic label, which leads to prohibitive synthetic costs and time-intensive preparations. Here we describe a protocol for the preparation of C1-labeled α-amino acids using simple aldehyde catalysts in conjunction with [*C]CO2 (* = 14, 13, 11). This late-stage labeling strategy is enabled by the one-pot carboxylate exchange of unprotected α-amino acids with [*C]CO2. The protocol consists of three separate procedures, describing the syntheses of (±)-[1-13C]phenylalanine, (±)-[1-11C]phenylalanine and (±)-[1-14C]phenylalanine from unlabeled phenylalanine. Although the delivery of [*C]CO2 is operationally distinct for each experiment, each procedure relies on the same fundamental chemistry and can be executed by heating the reaction components at 50-90 °C under basic conditions in dimethylsulfoxide. Performed on scales of up to 0.5 mmol, this methodology is amenable to C1-labeling of many proteinogenic α-amino acids and nonnatural derivatives, which is a breakthrough from existing methods. The synthesis of (±)-[1-13C]phenylalanine requires ~2 d, with product typically obtained in a 60-80% isolated yield (n = 3, µ = 71, σ = 8.3) with an isotopic incorporation of 70-88% (n = 18, µ = 72, σ = 9.0). Starting from the preformed imino acid (~3 h preparation time), rapid synthesis of (±)-[1-11C]phenylalanine can be completed in ~1 h with an isolated radiochemical yield of 13%. Finally, (±)-[1-14C]phenylalanine can be accessed in ~2 d with a 51% isolated yield and 11% radiochemical yield.

The biportal transorbital approach: quantitative comparison of the anterior subfrontal craniotomy, bilateral transorbital endoscopic, and microscopic approaches.

OBJECTIVE: The aim of this study was to assess the surgical use and applicability of a biportal bitransorbital approach. Single-portal transorbital and combined transorbital transnasal approaches have been used in clinical practice, but no study has assessed the surgical use and applicability of a biportal bitransorbital approach. METHODS: Ten cadaver specimens underwent midline anterior subfrontal (ASub), bilateral transorbital microsurgery (bTMS), and bilateral transorbital neuroendoscopic surgery (bTONES) approaches. Morphometric analyses included the length of the bilateral cranial nerves I and II, the optic tract, and A1; the area of exposure of the anterior cranial fossa floor; craniocaudal and mediolateral angles of attack (AOAs); and volume of surgical freedom (VSF; maximal available working volume for a specific surgical corridor and surgical target structure normalized to a height of 10 mm) of the bilateral paraclinoid internal carotid arteries (ICAs), bilateral terminal ICAs, and anterior communicating artery (ACoA). Analyses were conducted to determine whether the biportal approach was associated with greater instrument freedom. RESULTS: The bTMS and bTONES approaches provided limited access to the bilateral A1 segments and the ACoA, which were inaccessible in 30% (bTMS) and 60% (bTONES) of exposures. The average total frontal lobe area of exposure (AOE) was 1648.4 mm2 (range 1516.6-1958.8 mm2) for ASub, 1658.9 mm2 (1274.6-1988.2 mm2) for bTMS, and 1914.9 mm2 (1834.2-2014.2 mm2) for bTONES exposures, with no statistically significant superiority between any of the 3 approaches (p = 0.28). The bTMS and bTONES approaches were significantly associated with decreases of 8.7 mm3 normalized volume (p = 0.005) and 14.3 mm3 normalized volume (p < 0.001) for VSF of the right paraclinoid ICA compared with the ASub approach. No statistically significant difference in surgical freedom was noted between all 3 approaches when targeting the bilateral terminal ICA. The bTONES approach was significantly associated with a decrease of 105% in the (log) VSF of the ACoA compared with the ASub (p = 0.009). CONCLUSIONS: Although the biportal approach is intended to improve maneuverability within these minimally invasive approaches, these results illustrate the pertinent issue of surgical corridor crowding and the importance of surgical trajectory planning. A biportal transorbital approach provides improved visualization but does not improve surgical freedom. Furthermore, although it affords impressive anterior cranial fossa AOE, it is unsuitable for addressing midline lesions because the preserved orbital rim restricts lateral movement. Further comparative studies will elucidate whether a combined transorbital transnasal route is preferable to minimize skull base destruction and maximize instrument access.

Bundled Payments for Hip Fracture Surgery Are Associated With Improved Access, Quality, and Health Care Utilization, but Higher Costs for Complex Cases: An Interrupted Time Series Analysis.

OBJECTIVES: To study the impact of bundled payments for surgically managed hip fractures on care access, care quality, health care resource utilization, clinical impact, and acute care cost. DESIGN: An observational retrospective cohort study using a quasi-experimental design comparing prebundled and postbundled payments through an interrupted time series analysis. SETTING: A public acute care general hospital. PATIENTS: Patients 60 years and older, with surgery for an isolated, unilateral, nonpathological hip fracture during 2014-first quarter of 2019 [diagnosis-related group codes: I03A, I03B, I08A, and I08B] and transferred to specific rehabilitation institutions were studied. INTERVENTION: Bundled payments for funder-to-provider reimbursement. MAIN OUTCOMES MEASUREMENTS: Care access, care quality, health care resource utilization, clinical impact, and cost. RESULTS: Of 1477 patients, 811 were assigned to prebundled and 666 to postbundled payments. Although there was an improving trend of ward admission waiting times during postbundled payments [odds ratio (OR) = 1.14; 95% confidence interval (CI): 1.02-1.28], ward admission waiting times were longer when compared with prebundled payments (OR = 0.45; 95% CI: 0.23-0.85). Rates of 30-day all-cause readmissions were lower (OR = 0.08; 95% CI: 0.01-0.67), and trends of reducing inpatient rehabilitation and overall episode length of stay (OR = 1.26; 95% CI: 1.16-1.37 and OR = 1.17; 95% CI: 1.07-1.28, respectively) were demonstrated during postbundled payments. Acute care cost for complex cases were higher (OR = 0.49; 95% CI: 0.26-0.92) during bundled payments, compared with prebundled payments. CONCLUSIONS: Bundled payments for surgically managed hip fractures were associated with benefits for several outcomes pertinent to clinical improvement initiatives. More work, especially concerning cost-effective surgical implants and better care cost computations, are critically needed to contain the growth of acute medical care cost for these patients. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Toward "bigger" data for neurosurgical anatomical research: a single centralized quantitative neurosurgical anatomy platform.

Quantitative neurosurgical anatomy research aims to produce surgically applicable knowledge for improving operative decision-making using measurements from anatomical dissection and tools such as stereotaxis. Although such studies attempt to answer similar research questions, there is little standardization between them, offering minimal comparability. Modern technology has been incorporated into the research methodology, but many scientific principles are lacking, and results are not broadly applicable or suitable for evaluating big-data trends. Advances in information technology and the concept of big data permit more accessible and robust means of producing valuable, standardized, reliable research. A technology project, "Inchin," is presented to address these needs for neurosurgical anatomy research. This study applies the concept of big data to neurosurgical anatomy research, specifically in quantifying surgical metrics. A remote-hosted web application was developed for computing standard neurosurgical metrics and storing measurement data. An online portal (Inchin) was developed to produce a database to facilitate and promote neurosurgical anatomical research, applying optimal scientific methodology and big-data principles to this recent and evolving field of research. Individual data sets are not insignificant, but a collective of data sets present advantages. Large data sets allow confidence in data trends that are usually obscured in smaller numbers of samples. Inchin, a single centralized software platform, can act as a global database of results of neurosurgical anatomy studies. A calculation tool ensuring standardized peer-reviewed methodology, Inchin is applied to the analysis of neurosurgical metrics and may promote efficient study collaboration within and among neurosurgical laboratories.

Aldehyde-catalysed carboxylate exchange in α-amino acids with isotopically labelled CO2.

The isotopic labelling of small molecules is integral to drug development and for understanding biochemical processes. The preparation of carbon-labelled α-amino acids remains difficult and time consuming, with established methods involving label incorporation at an early stage of synthesis. This explains the high cost and scarcity of C-labelled products and presents a major challenge in 11C applications (11C t1/2 = 20 min). Here we report that aldehydes catalyse the isotopic carboxylate exchange of native α-amino acids with *CO2 (* = 14, 13, 11). Proteinogenic α-amino acids and many non-natural variants containing diverse functional groups undergo labelling. The reaction probably proceeds via the trapping of *CO2 by imine-carboxylate intermediates to generate iminomalonates that are prone to monodecarboxylation. Tempering catalyst electrophilicity was key to preventing irreversible aldehyde consumption. The pre-generation of the imine carboxylate intermediate allows for the rapid and late-stage 11C-radiolabelling of α-amino acids in the presence of [11C]CO2.

Volumetric 3-Dimensional Analysis of the Supraorbital vs Pterional Approach to Paramedian Vascular Structures: Comprehensive Assessment of Surgical Maneuverability.

BACKGROUND: Both the pterional and supraorbital approaches have been proposed as optimal access corridors to deep and paramedian anatomy. OBJECTIVE: To assess key intracranial structures accessed through the surgical approaches using the angle of attack (AOA) and the volume of surgical freedom (VSF) methodologies. METHODS: Ten pterional and 10 supraorbital craniotomies were completed. Data points were measured using a neuronavigation system. A comparative analysis of the craniocaudal AOA, mediolateral AOA, and VSF of the ipsilateral paraclinoid internal carotid artery (ICA), terminal ICA, and anterior communicating artery (ACoA) complex was completed. RESULTS: For the paraclinoid ICA, the pterional approach produced larger craniocaudal AOA, mediolateral AOA, and VSF than the supraorbital approach (28.06° vs 10.52°, 33.76° vs 23.95°, and 68.73 vs 22.59 mm3 normalized unit [NU], respectively; P < .001). The terminal ICA showed similar superiority of the pterional approach in all quantitative parameters (27.43° vs 11.65°, 30.62° vs 25.31°, and 57.41 vs 17.36 mm3 NU; P < .05). For the ACoA, there were statistically significant differences between the results obtained using the pterional and supraorbital approaches (18.45° vs 10.11°, 29.68° vs 21.01°, and 26.81 vs 16.53 mm3 NU; P < .005). CONCLUSION: The pterional craniotomy was significantly superior in all instrument maneuverability parameters for approaching the ipsilateral paraclinoid ICA, terminal ICA, and ACoA. This global evaluation of 2-dimensional and 3-dimensional surgical freedom and instrument maneuverability by amalgamating the craniocaudal AOA, mediolateral AOA, and VSF produces a comprehensive assessment while generating spatially and anatomically accurate corridor models that provide improved visual depiction for preoperative planning and surgical decision-making.

Enantioselective Tertiary Electrophile (Hetero)Benzylation: Pd-Catalyzed Substitution of Isoprene Monoxide with Arylacetates*.

The enantioselective generation of quaternary carbon centers remains challenging but is of growing importance for the preparation of functional molecules. Metal catalyzed allylic alkylations of tertiary electrophiles can provide access to these substructures but remain generally incompatible with organometallic benzyl nucleophiles. Here we demonstrate that electron-deficient arylacetates can serve as benzyl nucleophile surrogates to generate enantioenriched acyclic molecules containing a quaternary carbon center via a two-step substitution-decarboxylation process using isoprene monoxide. Products are often obtained in >90 % ee using a commercially available catalyst. An array of electron-withdrawing functional groups on the arylacetate moiety are tolerated. The lactone generated by the initial substitution reaction can be used in further stereoselective transformations to prepare molecules with acyclic vicinal quaternary stereocenters.

Development and implementation of an ultralow-dose CT protocol for the assessment of cerebrospinal shunts in adult hydrocephalus.

BACKGROUND: Cerebrospinal fluid shunts in the treatment of hydrocephalus, although associated with clinical benefit, have a high failure rate with repeat computed tomography (CT) imaging resulting in a substantial cumulative radiation dose. Therefore, we sought to develop a whole-body ultralow-dose (ULD) CT protocol for the investigation of shunt malfunction and compare it with the reference standard, plain radiographic shunt series (PRSS). METHODS: Following ethical approval, using an anthropomorphic phantom and a human cadaveric ventriculoperitoneal shunt model, a whole-body ULD-CT protocol incorporating two iterative reconstruction (IR) algorithms, pure IR and hybrid IR, including 60% filtered back projection and 40% IR was evaluated in 18 adult patients post new shunt implantation or where shunt malfunction was suspected. Effective dose (ED) and image quality were analysed. RESULTS: ULD-CT permitted a 36% radiation dose reduction (median ED 0.16 mSv, range 0.07-0.17, versus 0.25 mSv (0.06-1.69 mSv) for PRSS (p = 0.002). Shunt visualisation in the thoracoabdominal cavities was improved with ULD-CT with pure IR (p = 0.004 and p = 0.031, respectively) and, in contrast to PRSS, permitted visualisation of the entire shunt course (p < 0.001), the distal shunt entry point and location of the shunt tip in all cases. For shunt complications, ULD-CT had a perfect specificity. False positives (3/22, 13.6%) were observed with PRSS. CONCLUSIONS: At a significantly reduced radiation dose, whole body ULD-CT with pure IR demonstrated diagnostic superiority over PRSS in the evaluation of cerebrospinal fluid shunt malfunction.

Transorbital Neuroendoscopic Surgery as a Mainstream Neurosurgical Corridor: A Systematic Review.

BACKGROUND: Transorbital neuroendoscopic surgery (TONES) offers a new level of minimally invasive, minimally disfiguring skull base surgery with maximal surgical visualization. METHODS: This review systematically assesses the body of published anatomic (cadaveric) and clinical evidence for the approach. PubMed, Cochrane Library, Ovid MEDLINE, and Embase were systematically searched for articles in which the TONES surgical technique was used in an anatomic, clinical, or combined study. The outcomes of interest included identification of the diseases, operative outcomes, and complication rates. RESULTS: Twenty-three articles were selected for this systematic review: 10 were purely anatomic, 10 were clinical, and 3 had both clinical and cadaveric components. The articles reported 69 patients undergoing transorbital or combined transorbital and transnasal intervention. A total of 30 cases of cerebrospinal fluid leak were documented; of these, 28 (93%) had successful resolution, 2 (7%) had recurrence, and 5 (15%) experienced complications. A total of 31 tumors were biopsied (n = 1), resected (n = 22), or debulked (n = 8). Meningiomas were the most common lesion managed via TONES, with 5 of 7 patients with meningioma who reported preoperative neurologic deficits experiencing an improvement in extraocular movement impairment, visual acuity, proptosis, and ptosis. Transient postoperative clinical sequelae, including diplopia and ptosis, were increasingly associated with the superior lid crease incision and the sole transorbital approach. CONCLUSIONS: TONES is a significant development in transorbital skull base surgery. However, comprehensive, robust, comparative analyses and increasing use and generalizability of this technique in skull base surgery are awaited.

From Krönlein, through madness, to a useful modern surgery: the journey of the transorbital corridor to enter the neurosurgical armamentarium.

Transorbital surgery has gained recent notoriety because of its incorporation into endoscopic skull base surgery. The use of this surgical corridor has been pervasive throughout the 20th century. It has been utilized by multiple disciplines for both clinical and experimental purposes, although its historical origin is medically and ethically controversial. Hermann Knapp first introduced the orbital surgical technique in 1874, and Rudolf Krönlein introduced his procedure in 1889. Rivalry between Walter Dandy in neurosurgery and Raynold Berke in ophthalmology further influenced methods of tackling intracranial and intraorbital pathologies. In 1946, Walter Freeman revolutionized psychosurgery by completing seemingly successful transorbital leucotomies and promoting their minimally invasive and benign surgical characteristics. However, as Freeman's legacy came into disrepute, so did the transorbital brain access corridor, again resulting in its stunted evolution. Microsurgery and endoscopy further influenced the use, or lack thereof, of the transorbital corridor in neurosurgical approaches. Historical analysis of present goals in modern skull base surgery echoes the principles established through an approach described almost 150 years ago: minimal invasion, minimal morbidity, and priority of patient satisfaction. The progression of the transorbital approach not only reflects psychosocial influences on medical therapy, as well as the competition of surgical pioneers for supremacy, but also describes the diversification of skull base techniques, the impact of microsurgical mastery on circumferential neurosurgical corridors, the influence of technology on modernizing skull base surgery, and the advancing trend of multidisciplinary surgical excellence.

Oxidative cross-coupling processes inspired by the Chan-Lam reaction.

The Cu-catalyzed oxidative cross-coupling of N- and O-nucleophiles with aryl boronic acids (the Chan-Lam reaction) remains among the most useful approaches to prepare aniline and phenol derivatives. The combination of high chemoselectivity, mild reaction conditions, and the ability to use simple Cu-salts as catalysts makes this process a valuable alternative to aromatic substitutions and Pd-catalyzed reactions of aryl electrophiles (Buchwald-Hartwig coupling). Despite the widespread use of Chan-Lam reactions in synthesis, the analogous carbon-carbon bond forming variant of this process had not been developed prior to our work. This feature article describes our discovery and application of Cu-catalyzed oxidative coupling reactions of activated methylene derivatives or carboxylic acids with nucleophiles including aryl boronic esters and amines.

Biopsychosocial variations in quality of life outcome following microdiscectomy.

BACKGROUND: Lumbar microdiscectomy is one of the most frequently performed neurosurgical procedures. In this review, we ask why patients' outcomes vary so widely even within the same unit, with the same surgeon performing the procedure and utilizing the technique? METHODS: In a cohort of 87 patients, we investigated how/whether multiple patient variables impacted outcomes following single-level lumbar microdiscectomy. We studied whether early surgical intervention improved the patients' quality of life (QOL) versus late intervention. Furthermore, we assessed other variables that could influence patient-perceived improvement. Preoperatively and postoperatively, we additionally utilized the following internationally standardized questionnaires (EQ-5D, Oswestry, and Core Outcome Measures Index [COMI]). RESULTS: A generalized substantial improvement in QOL was identified throughout the cohort population (<0.05). There was no difference in health measurement scores for those undergoing early versus late surgery. However, there was a statistically significant improvement in all QOL scores for privately insured patients versus publicly insured patients (e.g., on COMI, EQ-5D, and ODI Scores). CONCLUSION: There was no objective statistically significant difference in QOL health scores between patients undergoing early versus late surgical lumbar microdiscectomy. This would suggest that the length of time patients is symptomatic before surgery did not significantly impact postoperative outcome. Of interest, however, was the difference in QOL health scores for private versus public patients suggesting that there are more subjective, complex, and psychosocial issues that influence outcome.

Deceptive Features on Surveillance Imaging of Intraneural Metastatic Deposits in Metastatic Renal Cell Cancer.

BACKGROUND: Spinal renal cell metastases are a common insidious pathological manifestation of the oncological process but less common are intramedullary and intraneural spinal metastases. The differential diagnosis of such pathological features can be difficult in the presence of conflicting radiological evidence. CASE DESCRIPTION: In the present case report, we have detailed the clinical, diagnostic, surgical, and therapeutic progression of a 54-year-old man diagnosed with metastatic renal cell carcinoma. After the initial presentation and treatment, he had presented with symptomatic right lower limb radiculopathy. Magnetic resonance imaging identified a well-defined cystic lesion expanding in the right exit foramina at L5-S1, suggestive of a benign schwannoma. After a multidisciplinary review, he was treated symptomatically and imaging surveillance for a 19-month period, with static lesion findings. Failure of symptomatic management resulted in operative intervention and subsequent histological diagnosis of the metastatic deposit. CONCLUSION: To the best of our knowledge, the present report is the first documented case of intraneural metastatic deposits from renal cell carcinoma that showed benign radiographic features and demonstrated a stable appearance on surveillance imaging studies for a significant period. These findings suggest that clinicians should have a high index of suspicion for a metastatic process in symptomatic patients with a known renal cell cancer regardless of the lesion's radiographic or temporal characteristics.

Intra-operative imaging for spinal level localisation in lumbar surgery.

Study Design: Retrospective review of the practice of 3 surgeons in a single centre during a 1-year period. Objective: We aimed to investigate our adherence to the Society of British Neurological Surgeons (SBNS) guidelines regarding intra-operative imaging during lumbar surgery and to determine if this has any impact on length of surgery or complications rates, in particular rates of wrong-level surgery. Background: The SBNS recommends three x-rays for intra-operative spinal localisation - one prior to incision, the second after exposure of the laminae and before the commencement of decompression, and the third at the end of the operation to confirm the adequacy of decompression. At our centre, surgeon A performs x-rays 1 and 3 routinely, and x-ray 2 in cases where the anatomy is uncertain, surgeon B performs x-ray 2 only, and the practice of surgeon C varies depending on the complexity of cases. Method: We reviewed the surgical logbooks of 3 consultant neurosurgeons in our centre for the 1-year period between October 2015 and October 2016. Our study included 301 patients who had undergone lumbar decompression or lumbar discectomy during this period. Results: There were no cases of wrong-level surgery. The incorrect spinal level was initially exposed in 13 cases (4.3%). 10 of these had x-ray 2 only, 1 had x-ray 1, 1 had x-rays 1 and 2, and 1 had all 3 x-rays. Surgeon B performed 8 of these cases, four were performed by surgeon C, and 1 by surgeon A. The median duration of surgery was 80 minutes for lumbar decompression and 67.5 minutes for lumbar discectomy. The median duration of surgery in patients in whom the wrong level was initially exposed was 85 minutes for lumbar decompression and 80 minutes for lumbar discectomy. Conclusion: Performance of the 3 recommended x-rays may increase the identification of wrong-level exposures before the commencement of decompression and may reduce the length of surgery.

Tendinopathic supraspinatus tenocytes may have a neuroendocrine-like function, secreting CGRP, SP and VEGF: a pilot immunohistochemistry study.

We wanted to observe and compare the appearance of neurovascular tissue from tendon ex vivo, in patients with and without painful rotator cuff tendinopathy. Supraspinatus tendons were biopsied from 5 participants with painful tendinopathy and normal tendon from a young male. Slides were stained with haematoxylin and eosin and toluidine blue for histological assessment. Immunohistochemical markers for general nerves (protein gene-product 9.5 and synaptophysin), sensory nerves (calcitonin gene-related peptide; substance-P) and vascularisation (vascular endothelial growth factor) were used. PGP9.5 and CGRP-immunoreactive fibres were associated with vessels in cases and control. Synaptophysinlabelled fibres were observed in close relation to vessels in tendinopathy. PGP9.5, CGRP, SP and VEGF-immunoreaction also labelled tenocyte-like cells in degenerative areas and fibres in regions of fat and collagen. Sensory innervation and vascularity are increased in tendinopathy. The evidence for innervation and vascularity of symptomatic rotator cuff tendon may aid the development of novel investigations and therapies in the management of patients with this ailment.

Multiplexed azido-group isotopic capture (MAGIC) beads: Selective analysis of azido compounds using a propargyl-based cleavable linker, a proof of concept.

RATIONALE: A cleavable linker is designed and synthesized for the selective capture of azide-containing compounds. This article presents a proof of concept methodology involving the use of peptide-functionalized aminopropyl silica, on which the peptide is constructed by solid-phase peptide synthesis. METHODS: The peptide linker has L-propargylglycine (Pra) at one terminal end to allow the conjugation of azide-containing molecules by copper assisted azide alkyne cycloaddition, also known as click reaction. L-Arginine (Arg) is placed just before Pra to permit the release of the captured product by tryptic cleavage. Three glycine (Gly) residues, as part of the linker, are appended to the silica bead to present a spacer section that allows efficient tryptic cleavage devoid of steric hindrance imposed by the bulky bead. The bead composition is Si-O-propyl-NH-Gly-Gly-Gly-Arg-Pra. RESULTS: This solid-phase material can be used to capture and release azide-functionalized compounds. The beads are first tested on three azido compounds, 2-azido-2-deoxyglucose (ADG), BOC-p-azido-Phe-OH (BAzPhe), where BOC = tert-butoxycarbonyl, and tetraacetylated-N-azidomannosamine (Ac4 ManNAz). Copper-mediated click reaction conditions are used and released products are characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and tandem MS (MS/MS). CONCLUSIONS: This method allows easy identification of captured compounds based on mass and fragmentation analysis. Moreover, it is useful for the analysis of small azide-containing compounds by MALDI-TOF-MS which may not be possible otherwise due to matrix interferences. The insertion of isotopically labeled Arg residues provides the possibility of multiplex analysis, from which the beads have been called MAGIC (for Multiplexed Azido-Group Isotopic Capture). Copyright © 2016 John Wiley & Sons, Ltd.

Homocysteine-induced endoplasmic reticulum protein (herp) is up-regulated in parkinsonian substantia nigra and present in the core of Lewy bodies.

BACKGROUND: Recent studies highlight the role of endoplasmic reticulum (ER) stress and aberrant protein degradation in the pathogenesis of neurodegenerative disorders. Herp which is encoded by the HERPUD 1 (homocysteine-inducible, endoplasmic reticulum stress-inducible, ubiquitin-like domain member 1) gene is a stress-response protein localized in the ER membrane of neurons and other cell types. Herp has been suggested to improve ER-folding, decrease ER protein load, and participate in ER-associated degradation (ERAD) of proteins. METHODS: Based on microarray expression profiling results we have predicted an increased expression of HERPUD1 in the substantia nigra of Parkinson's disease (PD) patients. We have now used brain tissue of some of the same and additional cases of sporadic PD to localize Herp mRNA and protein in individual cell types. RESULTS: We found expression of Herp in neurons and in glial cells including astrocytes. These findings were corroborated by in situ hybridization. Accumulation of Herp protein was also detected in the core of Lewy bodies suggesting a role in their formation. Hierarchical clustering analysis identified TWINKLE (PEO1) as the gene whose expression profile was most similar to that of Herp across the PD cohort. CONCLUSIONS: The nigral glial cells that expressed Herp at a high level resembled TUNEL-positive glia. While some of these cells likely undergo degeneration, the strong up-regulation of Herp in glia could help to explain the inflammation-like changes observed in PD ("neuroinflammation") as it has been shown that the unfolded protein response serves as an important regulator of inflammatory genes in other organs.

DnaJB6 is present in the core of Lewy bodies and is highly up-regulated in parkinsonian astrocytes.

DnaJ/Hsp40 chaperones determine the activity of Hsp70s by stabilizing their interaction with substrate proteins. We have predicted, based on the in silico analysis of a brain-derived whole-genome transcriptome data set, an increased expression of DnaJ/Hsp40 homologue, subfamily B, member 6 (DnaJB6) in Parkinson's disease (PD; Moran et al. [2006] Neurogenetics 7:1-11). We now show that DnaJB6 is a novel component of Lewy bodies (LBs) in both PD substantia nigra and PD cortex and that it is strongly up-regulated in parkinsonian astrocytes. The presence of DnaJB6 in the center of LBs suggests an early and direct involvement of this chaperone in the neuronal disease process associated with PD. The strong concomitant expression of DnaJB6 in astrocytes emphasizes the involvement of glial cells in PD and could indicate a route for therapeutic intervention. Extracellular alpha-synuclein originating from intravesicular alpha-synuclein is prone to aggregation and the potential source of extracellular aggregates (Lee [2008] J. Mol. Neurosci. 34:17-22). The observed strong expression of DnaJB6 by astrocytes could reflect a protective reaction, so reducing the neuronal release of toxic alpha-synuclein and supporting the astrocyte response in PD might limit the progression of the disease process.

Deafness alters auditory nerve fibre responses to cochlear implant stimulation.

Here we characterized the relationship between duration of sensorineural hearing loss and the response of the auditory nerve to electrical stimulus rate. Electrophysiological recordings were made from undeafened guinea pigs and those ototoxically deafened for either 5 weeks or 6 months. Auditory neuron survival decreased significantly with the duration of deafness. Extracellular recordings were made from auditory nerve fibres responding to biphasic, charge-balanced current pulses delivered at rates of 20 and 200 pulses/s via a monopolar scala tympani stimulating electrode. The response to 20 pulses/s electrical stimulation of the deafened cochlea exhibited a decrease in spike latency, unaltered temporal jitter and unaltered dynamic range (of nerve firing rate against stimulus current), and a reduction in threshold after 6 months of deafness. The response to a 200-pulse/s stimulus was similar except that the dynamic range was greater than with 20 pulses/s and was also greater in deafened animals than in undeafened animals. Deafness and pulse rate are related; in deaf animals spike recovery appears to be complete between successive stimulus pulses at a low rate (20 pulses/s), but incomplete between pulses at a moderate pulse rate (200 pulses/s). These results suggest that changes in the function of individual auditory nerve fibres after deafness may affect clinical responses during high-rate stimulation such as that used in contemporary speech processing strategies, but not during lower rate stimulation such as that used to record evoked potentials.

Effect of midazolam versus propofol sedation on markers of neurological injury and outcome after isolated severe head injury: a pilot study.

BACKGROUND: Midazolam and propofol are sedative agents commonly administered to patients with brain injury. We compared plasma concentrations of glial cell S100beta protein and nitric oxide (NO) between patients who received midazolam and those who received propofol sedation after severe brain injury, and investigated the association between S100beta and NO concentrations and neurological outcome. DESIGN: 28 patients with severe head injury (Glasgow Coma Score <9) who required sedation and ventilation were randomly assigned to receive midazolam (n =15) or propofol (n = 13) based sedation. Blood samples were drawn daily for 5 days for estimation of S100beta and NO concentrations. Neurological outcome was assessed 3 months later as good (Glasgow Outcome Score [GOS], 4-5) or poor (GOS, 1-3). RESULTS: A good neurological outcome was observed in 8/15 patients (53%) in the midazolam group and 7/13 patients (54%) in the propofol group. Patients with a poor outcome had higher serum S100beta concentrations on ICU admission and on Days 1-4 in the ICU than those with a good outcome (mean [SD] on Day 1, 0.99 [0.81] v 0.41 [0.4] microg/L; Day 2, 0.80 [0.81] v 0.41 [0.24] microg/L; Day 3, 0.52 [0.55] v 0.24 [0.25] microg/L; and Day 4, 0.54 [0.43] v 0.24 [0.35] microg/L; P<0.05). There was no significant difference on Day 5. Plasma NO concentrations were not associated with outcome. In subgroup analysis, there was no difference in S100beta and NO concentrations between patients with a good outcome versus those with a poor outcome in either the midazolam or propofol group. CONCLUSIONS: Plasma concentrations of markers of neurological injury in patients with severe head injury were similar in those who received midazolam sedation and those who received propofol. Patients who had a poor neurological outcome at 3 months had consistently higher serum S100beta concentrations during the initial 4 days after injury than patients who had a good outcome.