Synthesis and antimicrobial activities of N6-hydroxyagelasine analogs and revision of the structure of ageloximes.

(+)-N6-Hydroxyagelasine D, the enantiomer of the proposed structure of (-)-ageloxime D, as well as N6-hydroxyagelasine analogs were synthesized by selective N-7 alkylation of N6-[tert-butyl(dimethyl)silyloxy]-9-methyl-9H-purin-6-amine in order to install the terpenoid side chain, followed by fluoride mediated removal of the TBDMS-protecting group. N6-Hydroxyagelasine D and the analog carrying a geranylgeranyl side chain displayed profound antimicrobial activities against several pathogenic bacteria and protozoa and inhibited bacterial biofilm formation. However these compounds were also toxic towards mammalian fibroblast cells (MRC-5). The spectral data of N6-hydroxyagelasine D did not match those reported for ageloxime D before. Hence, a revised structure of ageloxime D was proposed. Basic hydrolysis of agelasine D gave (+)-N-[4-amino-6-(methylamino)pyrimidin-5-yl]-N-copalylformamide, a compound with spectral data in full agreement with those reported for (-)-ageloxime D.

Risk assessment of magnetic resonance imaging in chronically implanted paddle electrodes for cortical stimulation.

BACKGROUND: Cortical epidural stimulation is used for the treatment of different neuropsychiatric disorders such as chronic neuropathic pain, tinnitus, movement disorders, and psychiatric diseases. While preoperative magnetic resonance imaging (MRI) is considered the imaging tool of choice for planning the approach and electrode placement, postoperative MRI is still a contraindication with implanted paddle leads due to the risk of thermal damage or current induction creating seizures or neurological deficits. OBJECTIVES: In this feasibility in vitro study the temperature changes and induction were determined as well as the artifacts caused by 2 parallel paddle leads (Resume II, Model 3587 A; Medtronic, Minneapolis, Minn., USA), commonly used in clinical practice with and without a pulse generator (Prime Advanced, Model 7489; Medtronic). METHODS: An ultrasound gel-filled head phantom with 2 paddle leads mimicking the surgical scenario was used to evaluate temperature changes as well as induced currents in a 1.5- and 3-tesla MR scanner. In addition, 1 patient underwent a 3-tesla MRI with an implanted subdural paddle lead. RESULTS: Negligible temperature changes were detected with turbo spin echo sequences in the 1.5- and 3-tesla scanner using a head and body coil. Induced voltages up to 6 V were measured. The imaging artifacts in the phantom were well tolerable. The patient's imaging was uneventful under the settings which are accepted for deep brain stimulation imaging. CONCLUSION: MRI under the conditions described here seems to be safe with the implants used in this study. In particular, the induced temperature is much lower with paddle compared to conventional leads due to the different electrode design. The induced voltage does not carry any risks. However, these findings cannot automatically be transferred to other implants or other scanning conditions, and further studies are needed. The biomedical companies should be encouraged to develop MR-conditional paddle leads. Also, further research is necessary to study the mechanism of action of cortical stimulation in the future.

Demyelination reduces brain parenchymal stiffness quantified in vivo by magnetic resonance elastography.

The detection of pathological tissue alterations by manual palpation is a simple but essential diagnostic tool, which has been applied by physicians since the beginnings of medicine. Recently, the virtual "palpation" of the brain has become feasible using magnetic resonance elastography, which quantifies biomechanical properties of the brain parenchyma by analyzing the propagation of externally elicited shear waves. However, the precise molecular and cellular patterns underlying changes of viscoelasticity measured by magnetic resonance elastography have not been investigated up to date. We assessed changes of viscoelasticity in a murine model of multiple sclerosis, inducing reversible demyelination by feeding the copper chelator cuprizone, and correlated our results with detailed histological analyses, comprising myelination, extracellular matrix alterations, immune cell infiltration and axonal damage. We show firstly that the magnitude of the complex shear modulus decreases with progressive demyelination and global extracellular matrix degradation, secondly that the loss modulus decreases faster than the dynamic modulus during the destruction of the corpus callosum, and finally that those processes are reversible after remyelination.

Grading system for the selection of patients with congenital aural atresia for active middle ear implants.

INTRODUCTION: Active middle ear implants (aMEI) are being increasingly used for hearing restoration in congenital aural atresia. The existing gradings used for CT findings do not meet the requirements for these implants. Some items are expendable, whereas other important imaging factors are missing. We aimed to create a new grading system that could describe the extent of the malformation and predict the viability and challenges of implanting an aMEI. METHODS: One hundred three malformed ears were evaluated using HRCT of the temporal bone. The qualitative items middle ear and mastoid pneumatization, oval window, stapes, round window, tegmen mastoideum displacement and facial nerve displacement were included. An anterior- and posterior round window corridor, oval window and stapes corridor were quantified and novelly included. They describe the size of the surgical field and the sight towards the windows. RESULTS: The ears were graded on a 16-point scale (16-13 easy, 12-9 moderate, 8-5 difficult, 4-0 high risk). The strength of agreement between the calculated score and the performed implantations was good. The comparison of the new 16-point scale with the Jahrsdoerfer score showed that both were able to conclusively detect the high-risk group; however, the new 16-point scale was able to further determine which malformed ears were favorable for aMEI, which the Jahrsdoerfer score could not do. CONCLUSION: The Active Middle Ear Implant Score for aural atresia (aMEI score) allows more precise risk stratification and decision making regarding the implantation. The use of operative corridors seems to have significantly better prognostic accuracy than the Jahrsdoerfer score.

Biophysical modeling of brain tumor progression: from unconditionally stable explicit time integration to an inverse problem with parabolic PDE constraints for model calibration.

PURPOSE: A novel unconditionally stable, explicit numerical method is introduced to the field of modeling brain cancer progression on a tissue level together with an inverse problem (IP) based on optimal control theory that allows for automated model calibration with respect to observations in clinical imaging data. METHODS: Biophysical models of cancer progression on a tissue level are in general based on the assumption that the spatiotemporal spread of cancerous cells is determined by cell division and net migration. These processes are typically described in terms of a parabolic partial differential equation (PDE). In the present work a parallelized implementation of an unconditionally stable, explicit Euler (EE(⋆)) time integration method for the solution of this PDE is detailed. The key idea of the discussed EE(⋆) method is to relax the strong stability requirement on the spectral radius of the coefficient matrix by introducing a subdivision regime for a given outer time step. The performance is related to common implicit numerical methods. To quantify the numerical error, a simplified model that has a closed form solution is considered. To allow for a systematic, phenomenological validation a novel approach for automated model calibration on the basis of observations in medical imaging data is developed. The resulting IP is based on optimal control theory and manifests as a large scale, PDE constrained optimization problem. RESULTS: The numerical error of the EE(⋆) method is at the order of standard implicit numerical methods. The computing times are well below those obtained for implicit methods and by that demonstrate efficiency. Qualitative and quantitative analysis in 12 patients demonstrates that the obtained results are in strong agreement with observations in medical imaging data. Rating simulation success in terms of the mean overlap between model predictions and manual expert segmentations yields a success rate of 75% (9 out of 12 patients). CONCLUSIONS: The discussed EE(⋆) method provides desirable features for image-based model calibration or hybrid image registration algorithms in which the model serves as a biophysical prior. This is due to (i) ease of implementation, (ii) low memory requirements, (iii) efficiency, (iv) a straightforward interface for parameter updates, and (v) the fact that the method is inherently matrix-free. The explicit time integration method is confirmed via experiments for automated model calibration. Qualitative and quantitative analysis demonstrates that the proposed framework allows for recovering observations in medical imaging data and by that phenomenological model validity.

Lactam ergot alkaloids (ergopeptams) as predominant alkaloids in sclerotia of Claviceps purpurea from Norwegian wild grasses.

Four major alkaloids in the extracts from sclerotia of Claviceps purpurea, picked from wild grasses, have been identified as lactam (non-cyclol) ergot alkaloids. The structural information was obtained from ion trap MS and NMR spectroscopy. The data for one of the lactam ergot alkaloids were coinciding with ergocristam [N-(lysergyl-valyl)-cyclo(phenylalanyl-prolyl)]. The structural information of two further lactam alkaloids was suggestive of either alpha- or beta-ergocryptam [N-(lysergyl-valyl)-cyclo(leucyl-prolyl) or N-(lysergyl-valyl)-cyclo(isoleucyl-prolyl)] and ergoannam [N-(lysergyl-leucyl)-cyclo(leucyl-prolyl) or N-(lysergyl-isoleucyl)-cyclo(isoleucyl-prolyl)]. The constitution of the fourth lactam ergot alkaloid corresponded to N-(lysergyl-isoleucyl)-cyclo(phenylalanyl-prolyl), a new ergopeptam, which has not been described before. Additionally, the cyclol-analogue of the new ergopeptam was detected in the extracts and has been identified on the basis of its product ion spectrum from fragmentation of [M+H](+). The study described in this paper shows that lactam ergot alkaloids may not only be minor products of ergopeptine biosynthesis, as has been suggested hitherto, but may be major biosynthetic endproducts for some ergot strains. This is also the first report demonstrating the production of an ergot alkaloid that contains isoleucine as the second amino acid, i.e. the N-(lysergyl-isoleucyl)-moiety, by parasitic, naturally growing C. purpurea. This unusual type of ergot alkaloid has so far only been found in saprophytic cultures of C. purpurea.

An immunomodulating pectic polymer from Glinus oppositifolius.

An immunomodulating pectic polymer, GOA1, obtained from the aerial parts of the Malian medicinal plant Glinus oppositifolius (L.) Aug. DC. (Aizoaceae) has previously been reported to consist of arabinogalactans type I and II, probably linked to a rhamnogalacturonan backbone. To further elucidate the structure of the polymer GOA1, enzymatic degradation studies and weak acid hydrolysis were performed. Five different glycosidases were used, endo-alpha-D-(1-->4)-polygalacturonase, exo-alpha-L-arabinofuranosidase, endo-alpha-L-(1-->5)-arabinanase, endo-beta-D-(1-->4)-galactanase and exo-beta-D-galactosidase. It appears that GOA1 may contain a structural moiety consisting of a 1,3-linked galactopyranosyl (Galp) main chain with 1,6-linked Galp side chains attached to position 6 of the main chain. The 1,6-linked Galp side chain may be branched in position 3 with arabinofuranosyl (Araf) side chains. A 1,4-linked Galp backbone which might carry side chains or glycosyl units attached to position 3 is also a structural element in the polymer. We further show that GOA1 induce proliferation of B cells and the secretion of IL-1beta by macrophages, in addition to a marked increase of mRNA for IFN-gamma in NK-cells. To elucidate structure-activity relations the native polymer and the digested fractions were tested for complement fixing activity and intestinal immune stimulating activity. The partial removal of Araf residues after enzymatic degradations did not affect the bioactivities, while the acid hydrolysed fraction showed reduced complement fixing activity. A decrease in Araf units, 1,3,6-linked Galp units and a partial hydrolysed rhamnogalacturonan backbone, in addition to a reduction in molecular weight are factors that might have contributed to reduced bioactivity.

Identification of cytotoxic constituents of Narthecium ossifragum using bioassay-guided fractionation.

Narthecium ossifragum, a member of the Liliaceae family, contains phytochemicals that have hepatotoxic and nephrotoxic activity in several ruminant species. 3-Methoxyfuran-2(5H)-one has previously been isolated as the principal nephrotoxin, and its toxicity has been confirmed in vivo. However, previous investigations into the nephrotoxicity of N. ossifragum both in vivo and in vitro indicate that other phytochemical factors might contribute to the nephrotoxicity of the plant. In this study, the cytotoxicity in renal tubular cells (LLC-PK1) was measured using an aqueous extract from the plant and fractions from chromatographic separation to identify the cytotoxic constituents of the extract. In an iterative process two different groups of compounds were identified as the major cytotoxic principles in LLC-PK1 cells: steroidal saponins (primarily di- and trisaccharides of sarsasapogenin) and 5-hydroxy-4-methoxyfuran-2(5H)-one. Up to a concentration of 880 microg/mL (7.7 M) 3-methoxyfuran-2(5H)-one was not cytotoxic. The cytotoxicity of the saponins was abolished upon hydrolysis, indicating that the carbohydrate moiety of the molecule is a prerequisite for toxicity on the cellular level. The results of the present study have two important implications: first, the results question the direct involvement of 3-methoxyfuran-2(5H)-one in the nephrotoxicity of N. ossifragum; second, the findings should induce future investigations into the possible role of saponins in N. ossifragum-related nephrotoxicosis observed in ruminants that graze on this plant.

Sexual recruitment of the corals Favia fragum and Agaricia humilis in a 30-m(3) exhibit aquarium: species-specific limitations and implications on reproductive ecology.

We studied the recruitment of the Caribbean reef building corals Favia fragum (F. fragum) and Agaricia humilis(A. humilis) in captivity. Thirty colonies of each species collected in Curaçao, Netherlands Antilles, reproduced sexually during a temporary stay in a 30-m(3) closed system from November 2001-January 2002. Twelve months later, the F1 generation of F. fragum started reproducing and formed an F2 generation. No reproduction of the F1 recruits of A. humilis was observed. Two years after the introduction of the field colonies, sexual recruits of both species were assessed using two different methods: recruits were estimated using quadrats (quadrat sampling method) and the total number of recruits was counted by creating a map of the artificial rock work divided in distinct areas (area census method). Recruitment rates of F. fragum were highest for the F2 generation on horizontal surfaces (area census method: 137.9+/-191.7 recruits m(-2); quadrat sampling method: 272.0+/-254.8 recruits m(-2); mean+/-SD) and were overall lowest for the F1 generation on overhanging areas of the tank (area census method: 3.8+/-4.0 recruits m(-2); quadrat sampling method: 4.0+/-6.1 recruits m(-2); mean+/-SD recruits m(-2)). The populations of both species showed similar patterns independent of the applied assessment method with highest densities on horizontal surfaces followed by vertical surfaces and lowest densities on overhanging surfaces; however, both methods showed conflicting results when the influence of the surface orientation on the population densities was statistically analyzed. The maximum density of A. humilis (1.4+/-2.7 recruits m(-2) on horizontal surfaces) was much lower than the maximum density of the F1 generation of F. fragum (24.7+/-18.3 recruits m(-2)). Colony sizes of recruits within each population (F. fragum F1: 3.12+/-0.98 cm, F2: 0.83+/-0.41 cm; A. humilis F1: 3.79+/-1.35 cm; maximum diameter+/-SD) did not differ between different orientations (horizontal vs. vertical vs. overhanging). Calculated growth rates in the aquarium reflected those observed for F. fragum in the field, whereas A. humilis showed slower growth in the aquarium than in the field. Factors such as competition, sedimentation, and predation, that generally reduce in situ recruitment may be excluded in captivity resulting in far higher recruitment rates. This study confirms that aquarium exhibits can serve as a comparative model to study the ecology of corals under semi-controlled conditions. Zoo Biol 0:1-17, 2007. (c) 2007 Wiley-Liss, Inc.

New Seeding Approach Reduces Costs and Time to Outplant Sexually Propagated Corals for Reef Restoration.

The use of sexually propagated corals is gaining popularity as an approach for reef restoration. However, manually attaching substrates with recently settled corals to the reef using binding materials is both time-consuming and expensive, limiting the use of this technique to small spatial scales. We present a novel approach whereby young corals are 'seeded' on the reef without the need for manual attachment to the benthos. We tested two tetrapod-shaped concrete substrates (7.9 and 9.8 cm in diameter) on which coral larvae were settled. The tetrapods were efficiently deployed by wedging them in reef crevices, in 1.5 to 7% of the time required for traditional outplanting techniques. Seeding tetrapods was most effective in reefs with moderately to highly complex topographies, where they rapidly became lodged in crevices or cemented to the benthos by encrusting organisms. After one year, average recruit survival was 9.6% and 67% of tetrapods still harboured at least one coral colony, and overall, this approach resulted in a 5 to 18 fold reduction in outplanting costs compared to common outplanting methods. This seeding approach represents a substantial reduction in costs and time required to introduce sexually propagated corals to reefs, and could possibly enable larger scale reef restoration.

Isolation and identification of a cis-C8-diol-ester of okadaic acid from Dinophysis acuta in New Zealand.

A cis-isomer of a C(8)-diol ester of okadaic acid (1) was isolated during large-scale purification of pectenotoxins (PTXs) from extracts of Dinophysis acuta collected from the west coast of South Island, New Zealand. The compound was identified by NMR spectroscopic and liquid chromatography-mass spectrometry (LC-MS) studies, and is the first reported cis-isomer of an okadaic acid C(8)-diol-ester identified in Dinophysis. The more abundant trans-C(8)-diol ester of okadaic acid (2) isolated from the same Dinophysis extract was rapidly hydrolyzed to okadaic acid in vitro by the supernatant from green-lipped mussel hepatopancreas.

Identification of fatty acid esters of pectenotoxin-2 seco acid in blue mussels (Mytilus edulis) from Ireland.

Pectenotoxins from marine dinoflagellates of the genus Dinophysis are rapidly hydrolyzed by many shellfish to give pectenotoxin-2 seco acid, which isomerizes to 7-epi-pectenotoxin-2 seco acid. Three series of fatty acid esters of pectenotoxin-2 seco acid (PTX-2 seco acid) and 7-epi-PTX-2 seco acid were detected by LC-MS analysis of extracts from blue mussels (Mytilus edulis) from Ireland. The locations of the fatty acid ester linkages were identified by a combination of LC-MSn in positive- and negative-ion modes, LC-MS analysis of the products from reaction of the esters with sodium periodate, and NMR analysis of purified samples of the two most abundant ester derivatives. The 37-O-acyl esters of PTX-2 seco acid were the most abundant, followed by the corresponding 11-O-acyl esters, accompanied by low levels of the 33-O-acyl esters. The most abundant fatty acid esters in the fractionated sample were, in order, the 16:0, 22:6, 14:0, 16:1, 18:4, and 20:5 fatty acids, although a wide array of other PTX-2 seco acid fatty acid esters were also present at low levels.

Black perithecial pigmentation in Fusarium species is due to the accumulation of 5-deoxybostrycoidin-based melanin.

Biosynthesis of the black perithecial pigment in the filamentous fungus Fusarium graminearum is dependent on the polyketide synthase PGL1 (oPKS3). A seven-membered PGL1 gene cluster was identified by over-expression of the cluster specific transcription factor pglR. Targeted gene replacement showed that PGL1, pglJ, pglM and pglV were essential for the production of the perithecial pigment. Over-expression of PGL1 resulted in the production of 6-O-demethyl-5-deoxybostrycoidin (1), 5-deoxybostrycoidin (2), and three novel compounds 5-deoxybostrycoidin anthrone (3), 6-O-demethyl-5-deoxybostrycoidin anthrone (4) and purpurfusarin (5). The novel dimeric bostrycoidin purpurfusarin (5) was found to inhibit the growth of Candida albicans with an IC50 of 8.0 +/- 1.9 µM. The results show that Fusarium species with black perithecia have a previously undescribed form of 5-deoxybostrycoidin based melanin in their fruiting bodies.

2-Amino-14,16-dimethyloctadecan-3-ol, a new sphingosine analogue toxin in the fungal genus Fusarium.

2-Amino-14,16-dimethyloctadecan-3-ol (2-AOD-3-ol) was isolated from the cytotoxic rice culture extract of a strain of Fusarium avenaceum, which had previously been isolated from Norwegian grain. The structural information was obtained from LC-MS/MS, GC-MS, NMR spectroscopy and high-resolution MS data. The metabolite has a striking similarity to sphinganine, an intermediate in the biosynthesis of the sphingolipids. This similarity is a major feature of the so-called sphingosine analogue toxins; the most studied being the AAL toxins and the fumonisins. 2-AOD-3-ol was found to be cytotoxic to the rat hepatoma cell line H4IIE-W and to the porcine epithelial kidney cell line PK(15) at concentrations (EC(50)) of 16 and 24 microM, respectively. The metabolite has been found in F. avenaceum inoculated wheat that was treated to support ideal conditions for Fusarium growth, demonstrating that the fungus has the potential to produce the metabolite under field conditions, which may occur in Northern Europe.

Zebra sign: cerebellar bleeding pattern characteristic of cerebrospinal fluid loss. Case report.

Supratentorial subdural hematoma is a well-known complication following spinal interventions. Less often, spinal or supratentorial interventions cause remote cerebellar hemorrhage (RCH). The exact pathomechanism accounting for RCH remains unclear, but an interventional or postinterventional loss of cerebrospinal fluid (CSF) seems to be involved in almost all cases. Hemorrhage is often characterized by a typical, streaky bleeding pattern due to blood spreading in the cerebellar sulci. Three different cases featuring this bleeding pattern following spinal, supratentorial, and thoracic surgery are presented. Possible pathomechanisms leading to RCH are discussed. Based on data from the underlying cases and the reviewed literature, the authors concluded that this zebra-pattern hemorrhage seems to be typical in a postoperative loss of CSF, which should always be considered on presentation of this bleeding pattern.

Technical note: A toy as tool: a low-cost image analysis system for the evaluation of tumor size in experimental small animal models.

Image analysis systems are an essential tool in measurements of size of intraparenchymal tumors or lesions in experimental small animal models. Conventional image analysis systems are relatively expensive. We therefore compared the performance of a professional image analysis system with an inexpensive setup by evaluating tumor size in an orthotopic glioma mouse model. The maximum cross-sectional tumor area of H&E stained brain-slides of two groups of mice (treatment and control group) was measured by two independent investigators using a professional image analysis system (Leica DM IRB microscope) with the Leica Quantimet 500c software, and a low-cost-system (Intel QX3 microscope) with a non-commercial image analysis software. Mean tumor volumes were calculated and the results from each of the image analysis systems, investigators, and treatment effects were compared. The tumor volumes as measured with the low-cost and the professional system differed between -3.7 and +7.5% (P = 0.69-0.99). Measurements made by investigator A and B differed between -7.0 and +3.9% (P = 0.69-0.88). Treatment in all cases significantly reduced the tumor volume between 58.4 and 62.7% (P = 0.0002 or 0.0003), regardless of the investigator or the used image analysis system. We therefore conclude that the QX3 low-cost microscope in combination with a non-commercial image-analysis software represents an inexpensive solution to reliably analyze the size of regions of interest, if they provide a sufficient contrast. However, the low-cost setup due to its low resolution definitely limits a detailed analysis of histologic features.

Prenylated flavonoids, monoterpenoid furanocoumarins and other constituents from the twigs of Dorstenia elliptica (Moraceae).

A monoprenylated flavan and two monoterpenoid substituted furanocoumarins were isolated from the twigs of Dorstenia elliptica along with 3-(3,3-dimethylallyl)-4,2',4'-trihydroxylchalcone, psoralen, bergapten, O-[3-(2,2-dimethyl-3-oxo-2H-furan-5-yl)butyl]bergaptol, beta-sitosterol and its beta-D-glucopyranoside. The structure of the flavan was determined as 6(1,1-dimethylallyl)-7,4'-dihydroxylflavan and the monoterpenoid substituted furanocoumarins were assigned as O-[3-(2,2-dimethyl-3-oxo-2H-furan-5-yl)-3-hydroxybutyl]-bergaptol and O-[2-(5-hydroxy-2,6,6-trimethyl-3-oxo-2H-pyran-2-yl)ethyl]bergaptol, respectively, using spectroscopic analysis, especially, 2D NMR spectra.

Complete asymptomatic thrombosis and resorption of a congenital giant intracranial aneurysm.

Intracranial aneurysms in infants are rare, but are associated with a high risk of rupture and subarachnoid hemorrhage. The authors report a case of an incidentally diagnosed, probably congenital, asymptomatic giant aneurysm of the posterior communicating artery in a 9-month-old girl, which completely thrombosed following a diagnostic superselective angiography without any neuropathological incident. Follow-up magnetic resonance imaging revealed that the aneurysm decreased further in size and was largely resorbed within 3 years after the initial finding. In single cases the natural history of congenital giant aneurysms may be better than previously assumed.

Frontoethmoidal encephalocele with ocular leakage of cerebrospinal fluid. Case report.

The authors present the case of a 2-year-old boy who was born with a small bulging mass in the middle frontonasal area and hypertelorism. In the neonatal period he suffered from a continuous lacrimal secretion mistaken for recurrent conjunctivitis. Cranial computerized tomography scanning and magnetic resonance imaging revealed a frontoethmoidal encephalocele associated with an ocular leakage of cerebrospinal fluid. One-stage repair of the encephalocele, along with correction of hypertelorism and bone grafting of the forehead, was performed with good result. During a 2-year follow-up period no neurological deficits appeared.