The Effect of Block Ratio and Structure on the Thermosensitivity of Double and Triple Betaine Block Copolymers.

AB-type and BAB-type betaine block copolymers composed of a carboxybetaine methacrylate and a sulfobetaine methacrylate, PGLBT-b-PSPE and PSPE-b-PGLBT-b-PSPE, respectively, were synthesized by one-pot RAFT polymerization. By optimizing the concentration of the monomer, initiator, and chain transfer agent, block extension with precise ratio control was enabled and a full conversion (~99%) of betaine monomers was achieved at each step. Two sets (total degree of polymerization: ~300 and ~600) of diblock copolymers having four different PGLBT:PSPE ratios were prepared to compare the influence of block ratio and molecular weight on the temperature-responsive behavior in aqueous solution. A turbidimetry and dynamic light scattering study revealed a shift to higher temperatures of the cloud point and micelle formation by increasing the ratio of PSPE, which exhibit upper critical solution temperature (UCST) behavior. PSPE-dominant diblocks created spherical micelles stabilized by PGLBT motifs, and the transition behavior diminished by decreasing the PSPE ratio. No particular change was found in the diblocks that had an identical AB ratio. This trend reappeared in the other set whose entire molecular weight approximately doubled, and each transition point was not recognizably impacted by the total molecular weight. For triblocks, the PSPE double ends provided a higher probability of interchain attractions and resulted in a more turbid solution at higher temperatures, compared to the diblocks which had similar block ratios and molecular weights. The intermediates assumed as network-like soft aggregates eventually rearranged to monodisperse flowerlike micelles. It is expected that the method for obtaining well-defined betaine block copolymers, as well as the relationship of the block ratio and the chain conformation to the temperature-responsive behavior, will be helpful for designing betaine-based polymeric applications.

Excited-state dynamics of dipyrrolyldiketone difluoroboron complexes.

Anion-responsive photofunctional materials have been extensively studied because anions are important for biotic activity and constitute the building blocks of elegant supramolecular architectures. A number of fluorescent anion receptors that can probe anions in their environments have been reported, but the excited states of many of these molecules remain elusive. Studies on excited-state dynamics provide fruitful information for optimizing the emission properties, minimizing the photodegradation and photorelease of anions, and exploring novel photofunctions. In this study, we investigated the excited-state dynamics of an aryl-substituted dipyrrolyldiketone difluoroboron complex, a π-conjugated anion receptor, by time-resolved visible and infrared absorption spectroscopy and emission decay measurements combined with quantum chemical calculations. Anion binding was found to alter the radiative and nonradiative rate constants and the excited-state absorption of the anion receptor. In contrast, the molecular structures and binding abilities were similar in the S0 and S1 states.

Ultrafast excited state dynamics of nonfluorescent cyclopheophorbide-a enol, a catabolite of chlorophyll-a detoxified in algae-feeding aquatic microbes.

For photosynthetic organisms that nourish the earth's biosphere, chlorophylls (Chls) are the major pigments utilized for light harvesting and primary charge separation. Although Chl molecules are effective photosensitizers, they are inevitably phototoxic to living organisms due to the facile generation of highly oxidative singlet oxygen (1O2) through triplet energy transfer from their photoexcited states to oxygen molecules. Such phototoxicity of Chls is a major problem for translucent microbes that feed on photosynthetic algae. Recently, it has been reported that the metabolic conversion of Chls-a/b to 132,173-cyclopheophorbide-a/b enols (cPPB-a/bEs) is the detoxification mechanism for algivorous protists. cPPB-a/bEs are colored π-conjugated cyclic tetrapyrroles but are nonfluorescent due to efficient nonradiative decay. In this study, femtosecond time-resolved transient absorption spectroscopy was applied to cPPB-aE with the aim of understanding its quenching mechanism. As a result, we have captured the ultrafast generation of an intermediate state (∼140 fs) that leads to the rapid internal conversion to the ground state (∼450 fs).

In vivo and in vitro preparation of divinyl-132,173-cyclopheophorbide-a enol.

Divinyl-132,173-cyclopheophorbide-a enol was in vivo produced as a metabolite of divinyl-chlorophyll-a by protists and in vitro prepared by the intramolecular cyclization of methyl divinyl-pyropheophorbide-a, one of the divinyl-chlorophyll-a derivatives. The 1H NMR spectra in CDCl3 showed that the obtained product took exclusively its enol form in the solution. The intramolecular cyclization of chlorin π-system at the C132 and C173 positions affected the optical properties of such chlorophyll derivatives including the non-fluorescent emission of the enol.

Synthesis of chlorophyll-c derivatives by modifying natural chlorophyll-a.

Chlorophyll-a (Chl-a) was extracted from cyanobacterial cells and modified to methyl pyropheophorbide-a. The 3-vinyl-chlorin was transformed to zinc complex of the corresponding 3-acetyl-porphyrin. The zinc porphyrin was oxidized to give cis-7,8- and 17,18-dihydroxy-chlorins as well cis-7,8-cis-17,18-tetrahydroxybacteriochlorin. After zinc-demetallation, the isolated cis-7,8- and 17,18-diols were reduced at the 3-acetyl group and triply dehydrated under acidic conditions to afford two regioisomeric 3-vinyl-porphyrins, methyl divinyl-pyroprotopheophorbide-a possessing the 8-vinyl group and 17-propionate residue (one of the divinyl-protoChl-a derivatives) and methyl pyropheophorbide-c 1 possessing the 8-ethyl group and 17-acrylate residue (one of the Chl-c 1 derivatives), respectively. The resulting 7,8,17,18-tetrol was reduced and then acidically treated, giving five-fold dehydrated free base porphyrin, methyl pyropheophorbide-c 2 possessing the 3,8-divinyl groups and 17-acrylate residue (one of the Chl-c 2 derivatives). The visible absorption and fluorescence emission spectra of the three semi-synthetic 3-vinyl-porphyrins in dichloromethane were compared with those of the corresponding 8-ethyl-porphyrin bearing the 17-propionate residue, methyl pyroprotopheophorbide-a (one of the protoChl-a derivatives). The Soret and Qy absorption maxima were shifted to longer wavelengths with an increase of π-conjugation in a molecule: protoChl-a (8-CH2CH3/17-CH2CH2COOCH3) < divinyl-protoChl-a (8-CH=CH2/17-CH2CH2COOCH3) < Chl-c 1 (8-CH2CH3/17-CH=CHCOOCH3) < Chl-c 2 derivatives (8-CH=CH2/17-CH=CHCOOCH3). The 17(1),17(2)-dehydrogenation broadened the absorption bands. The emission maxima were bathochromically shifted in the same order. The reaction mechanism of the present dehydration indicates that the biosynthetic pathway of Chls-c would include the hydroxylation of the 17-propionate reside at the 17(1)-position and successive dehydration to the 17-acrylate residue.

Enhancement of Light Absorption Ability of Synthetic Chlorophyll Derivatives by Conjugation with a Difluoroboron Diketonate Group.

The enhancement of the light absorption ability of synthetic chlorophyll derivatives is demonstrated. Chlorophyll derivatives directly conjugated with a difluoroboron 1,3-diketonate group at the C3 position were synthesized from methyl pyropheophorbide-d through Barbier acylmethylation of the C3-formyl moiety, oxidation of the C3-carbinol, and difluoroboron complexation of the diketonate. Electronic absorption spectra in a diluted solution showed that the synthetic conjugates gave an absorption band at λ=400-500 nm, with a Qy band shifted to a longer wavelength of λ≈700 nm. DFT calculations demonstrated that the absorption bands and redshifts were ascribable to the coupling of the LUMO of chlorin with that of the difluoroboron diketonate moiety. The introduction of a pyrenyl group at the C3(3) -position of the conjugate afforded an additional charge-transfer band over λ=500 nm, producing a pigment that bridged the green gap in standard chlorophylls.

Daily Repetitive Transcranial Magnetic Stimulation for Poststroke Upper Limb Paresis in the Subacute Period.

BACKGROUND: We conducted a randomized, double-blind, sham-controlled study to assess the efficacy in motor recovery and safety of daily repetitive transcranial magnetic stimulation (rTMS) in subacute stroke patients. METHODS: Forty-one patients were randomly assigned to a real or sham stimulation group. Each patient underwent regular rehabilitation accompanied by a series of 10 daily 5-Hz rTMS of the ipsilesional primary motor cortex (M1) or sham stimulation. The primary outcome was motor recovery evaluated by the Brunnstrom stages (BS). The secondary outcomes were improvement in the Fugl-Meyer Assessment (FMA), grip power, National Institutes of Health Stroke Scale (NIHSS), Functional Independence Measure (FIM), a quantitative measurement of finger tapping movement, and the incidence of adverse events. RESULTS: Thirty-nine patients completed the study and were included in the analyses. The real rTMS group demonstrated additional improvement in the BS hand score at the last follow-up compared to the sham. The grip power, the NIHSS motor score, and the number of finger taps in the affected hand improved in the real stimulation group but not in the sham group. The BS upper limb scores, the FMA distal upper limb score, the NIHSS total score, and the FIM motor score showed improvement from baseline at the earlier time points after the real rTMS. There were no additional improvements in the other scores after the real rTMS compared to the sham. No serious adverse events were observed. CONCLUSIONS: Our results suggest that dailyhigh-frequency rTMS of the ipsilesional M1 is tolerable and modestly facilitates motor recovery in the paralytic hand of subacute stroke patients.

Ubiquity and quantitative significance of detoxification catabolism of chlorophyll associated with protistan herbivory.

Chlorophylls are essential components of the photosynthetic apparati that sustain all of the life forms that ultimately depend on solar energy. However, a drawback of the extraordinary photosensitizing efficiency of certain chlorophyll species is their ability to generate harmful singlet oxygen. Recent studies have clarified the catabolic processes involved in the detoxification of chlorophylls in land plants, but little is understood about these strategies in aquatic ecosystem. Here, we report that a variety of heterotrophic protists accumulate the chlorophyll a catabolite 13(2),17(3)-cyclopheophorbide a enol (cPPB-aE) after their ingestion of algae. This chlorophyll derivative is nonfluorescent in solution, and its inability to generate singlet oxygen in vitro qualifies it as a detoxified catabolite of chlorophyll a. Using a modified analytical method, we show that cPPB-aE is ubiquitous in aquatic environments, and it is often the major chlorophyll a derivative. Our findings suggest that cPPB-aE metabolism is one of the most important, widely distributed processes in aquatic ecosystems. Therefore, the herbivorous protists that convert chlorophyll a to cPPB-aE are suggested to play more significant roles in the modern oceanic carbon flux than was previously recognized, critically linking microscopic primary producers to the macroscopic food web and carbon sequestration in the ocean.

Synthesis of chlorophyll-f analogs possessing the 2-formyl group by modifying chlorophyll-a.

A methyl group at the 2-position of methyl mesopyropheophorbide-a was transformed to the 2-formyl group to give methyl mesopyropheophorbide-f, one of the chlorophyll-f analogs. The 2-formylation moved the redmost electronic absorption band in a solution to a longer wavelength and the bathochromic shift was comparable to that by the 3-formylation. Zinc complex of the synthetic compound in solutions showed similar visible absorption spectra as those of naturally occurring chlorophyll-f.

Solitary and Synergistic Effects of Different Hydrophilic and Hydrophobic Phospholipid Moieties on Rat Behaviors.

Glycerophospholipids have hydrophobic and hydrophilic moieties. Previous studies suggest that phospholipids with different moieties have different effects on rodent behavior; however, the relationship between chemical structures and behavioral effects remains unclear. To clarify the functions of phospholipid moieties, we injected male rats with phospholipids with different moieties and conducted behavioral tests. Exploratory activity was reduced by phosphatidylethanolamine (PE)(18:0/22:6) but not PE(18:0/18:0) or PE(18:0/20:4). Conversely, exploratory activity was increased by plasmanyl PE(16:0/22:6), which harbors an alkyl-ether linkage, but not by phosphatidylcholine (PC)(16:0/22:6) or plasmanyl PC(16:0/22:6). Docosahexaenoic acid (DHA)(22:6) and an alkyl-ether linkage in PE were thus postulated to be involved in exploratory activity. Anxiety-like behavior was reduced by plasmenyl PC(18:0/20:4), which harbors a vinyl-ether linkage, but not by PC(18:0/20:4) or plasmanyl PC(18:0/20:4), suggesting the anxiolytic effects of vinyl-ether linkage. The activation of social interaction was suppressed by PE(18:0/18:0), PE(18:0/22:6), PC(16:0/22:6), plasmanyl PE(16:0/22:6), and plasmanyl PC(16:0/22:6) but not by PE(18:0/20:4), plasmenyl PE(18:0/20:4), or plasmanyl PC(18:0/22:6). DHA may suppress social interaction, whereas arachidonic acid(20:4) or a combination of alkyl-ether linkage and stearic acid(18:0) may restore social deficits. Our findings indicate the characteristic effects of different phospholipid moieties on rat behavior, and may help to elucidate patterns between chemical structures and their effects.

Synthesis, structure, and optical and redox properties of chlorophyll derivatives directly coordinating ruthenium bisbipyridine at the peripheral ß-diketonate moiety.

The diketonate group of the peripheral position in chlorophyll derivatives 1 and 2 coordinated ruthenium bisbipyridine to give direct linkages 3-5 of the chlorin ring with the Ru(II) complex. Zinc metalation of the central position in the chlorin ring of free base 3 afforded the Ru-Zn binuclear complex 3-Zn. Because the diketonate group at the C3 position of chlorophyll derivatives coordinated to bulky Ru(bpy)2(2+), the plane of the diketonate group was twisted from the chlorin π ring in synthetic 3-5 and 3-Zn to lead to a partial deconjugation and a slight blue shift of the longest wavelength electronic absorption band in dichloromethane. A broad metal-to-ligand charge-transfer absorption band derived from the Ru complex was observed around 500 nm, in addition to visible absorption bands from the chlorophyll moiety. Chlorophyll derivatives 3-5 and 3-Zn directly coordinating the ruthenium complex were less fluorescent in dichloromethane than chlorophyll-diketonate ligands 1, 2, and 1-Zn due to the heavy atom effect of the ruthenium in a molecule. The coordination to the ruthenium complex moiety at the peripheral position shifted the electrochemical reduction of the chlorin part in acetonitrile to a negative potential, and the coordination to zinc at the central position decreased the redox potentials. Chemical modification of the bipyridine and diketonate ligands of the ruthenium complexes greatly affected the redox potentials of Ru(II)/(III) and/or Ru(II)/(I) but minimally the redox properties of the chlorin moiety. Substitution with electron-donating groups shifted the former to a negative potential but only barely shifted the latter. The zinc metalation caused no apparent shifts for the redox potentials of the Ru center.

Photoinduced Catalytic Organic-Hydride Transfer to CO2 Mediated with Ruthenium Complexes as NAD+ /NADH Redox Couple Models.

The catalytic organic-hydride transfer to CO2 was first achieved through the photoinduced two-electron reduction of the [Ru(bpy)2 (pbn)]2+ /[Ru(bpy)2 (pbnHH)]2+ (bpy=2,2'-bipyridine, pbn=2-(pyridin-2-yl)benzo[b]-1,5-naphthyridine, and pbnHH=2-(pyridin-2-yl)-5,10-dihydrobenzo[b]-1,5-naphthyridine) redox couple in the presence of 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole (BIH). The active species for the catalytic hydride transfer to carbon dioxide giving formate is [Ru(bpy)(bpy⋅- )(pbnHH)]+ formed by one-electron reduction of [Ru(bpy)2 (pbnHH)]2+ with BI⋅.

Water coordinated zinc dioxo-chlorin and porphyrin self-assemblies as chlorosomal mimics: variability of supramolecular interactions.

Semisynthetic zinc chlorins are shown for the first time to self-assemble in the absence of an intrinsic hydroxy group, which is always present in the chlorosomal bacteriochlorophylls (BChl's) c, d and e. Instead, the presently studied compounds have carbonyl groups. These cannot function as hydrogen bond donating groups. However due to interspacing water molecules bound to the zinc ion, double hydrogen bonding can occur to adjacent tetrapyrrolic macrocycles equipped with carbonyl recognition groups. Solution studies comprising UV-Vis absorption, electronic circular dichroism (ECD) and FT-IR show that different aggregates are formed in hydrated solvents in comparison to dry nonpolar solvents. Single crystal X-ray studies show variable supramolecular interactions either with interspacing water molecules coordinating the Zn ion within a porphyrin or with the 17(2) carbonyl group of a chlorin ligating the Zn ion. Our findings have implications for a minimalistic design of self-assembling chromophores, which can act as efficient light-harvesting units.

Determination of the critical chain length for macromolecular crystallization using structurally flexible polyketones.

Critical chain length that divides small molecule crystallization from macromolecular crystallization is an important index in macro-organic chemistry to predict chain-length dependent properties of oligomers and polymers. However, extensive research on crystallization behavior of individual oligomers has been inhibited by difficulties in their synthesis and crystallization. Here, we report on the determination of critical chain length of macromolecular crystallization for structurally flexible polyketones consisting of 3,3-dimethylpentane-2,4-dione. Discrete polyketone oligomers were synthesized via stepwise elongation up to 20-mer. Powder and single crystal X-ray diffraction showed that the critical chain length for polyketones existed at an unexpectedly short chain length, 5-mer. While shorter oligomers adopted unique conformations and packing structures in the solid state, higher oligomers longer than 4-mer produced helical conformations and similar crystal packing. The critical chain length helped with understanding the inexplicable changes in melting point in the shorter chain length region resulting from chain conformations and packing styles.

Retrolabyrinthine transsigmoid approach to complex parabrainstem tumors in the posterior fossa.

OBJECTIVE: The surgical management of large and complex tumors of the posterior fossa poses a formidable challenge in neurosurgery. The standard retrosigmoid craniotomy approach has been performed at most neurosurgical centers; however, the retrosigmoid approach may not provide enough working space without significant retraction of the cerebellum. The transsigmoid approach provides wider and shallower surgical fields; however, there have been few clinical and no cadaveric studies on its usefulness. In the present study, the authors describe the transsigmoid approach in clinical cases and cadaveric specimens. METHODS: For the clinical study, the authors retrospectively reviewed the medical records and operative charts of patients who had been surgically treated for parabrainstem tumors using the transsigmoid approach between 1997 and 2019. They analyzed patient demographic and clinical data, as well as surgical and clinical outcomes. In the cadaveric study, they compared the surgical views obtained in different approaches (retrosigmoid, presigmoid, retrolabyrinthine, and transsigmoid) and measured the sigmoid sinus width at the level of the endolymphatic sac and the distance between the anterior edge of the sigmoid sinus and the endolymphatic sac on 35 sides in 19 cadaveric specimens. RESULTS: A total of 21 patients (6 males and 15 females) with a mean age of 42.2 (range 15-67) years were included in the clinical study. Eleven patients had meningioma, 7 had vestibular schwannoma, 2 had hemangioblastoma, and 1 had epidermoid cyst. Gross-total, near-total, and subtotal removal were achieved in 7 (33.3%), 3 (14.3%), and 11 (52.4%) patients, respectively. In the cadaveric study, 19 cadaveric specimens were used. The sigmoid sinus was cut in the middle, and the incision was extended from the retrosigmoid to the presigmoid dura. The dura was then retracted upward and downward like opening a door. The results indicated that this technique can widen the operative field anteriorly by approximately 2 cm as compared to the retrosigmoid approach and provides a better view anterior to the brainstem. CONCLUSIONS: The transsigmoid approach is useful for complex parabrainstem tumors in the posterior fossa because it provides a wider and shallower operative view with less retraction of the cerebellum. This enables safer tumor removal with less damage to important structures in the posterior fossa, resulting in better operative and clinical outcomes.

Evaluation of Ceramics Adsorption Filter as a Pretreatment for Seawater Reverse-Osmosis Desalination.

Seawater reverse osmosis (SWRO) is the most energy-efficient process for desalination to produce drinking water from seawater. However, its sustainability is still challenged by membrane fouling. Appropriate feed water quality is one of the crucial prerequisites for SWRO operation. In the current study, a ceramic adsorption filter (CAF), which was predominantly coated with an aluminum-based adsorbent (i.e., Alumina, Al2O3), was employed to enhance the pretreatment performance of SWRO. The fouling performance of SWRO pre-treated with a CAF was evaluated by feeding with real ultrafiltration (UF)-filtrated seawater collected from a seawater desalination R&D facility in Singapore. The flux decline profile showed that the presence of CAF after UF could mitigate around 10-30% of SWRO fouling. Based on the autopsy of the fouled SWRO membranes, it was observed that SWRO with CAF pre-treatment and daily regeneration could alleviate around 77.5% of Ca-induced inorganic fouling as well as 76% of lower biofouling. The present work highlights the potential of applying adsorption technology to enhance pre-treatment performance to extend the lifespan of SWRO membranes. Coupling the adsorbents on a ceramic filter should be a useful way to ease their implementation, i.e., inline adsorption and re-generation.

Diffuse Cerebral Vasospasm After Removal of a Posterior Fossa Hemangioblastoma in a 62-Year-Old Woman.

BACKGROUND: The development of diffuse cerebral vasospasm after the removal of a brain tumor is extremely rare. We report a case of cerebral vasospasm after the removal of a posterior fossa hemangioblastoma. CASE DESCRIPTION: A 62-year-old woman presented with a 1-month history of vertigo and nausea. Neurologic examination revealed that she was alert, with no paresis, and a mild left-sided cerebellar ataxia. Contrast-enhanced magnetic resonance imaging showed a cystic lesion with a strongly enhancing nodule, measuring 20 × 26 mm in diameter, in the cerebellar dorsal vermis. Angiography revealed that the lesion had feeding arteries from the left posterior inferior cerebellar artery. A diagnosis of hemangioblastoma was suspected and surgery was performed. On the first postoperative day, paresis of the right-sided extremities occurred. Diffusion-weighted imaging showed a high-intensity area in the medial side of the left frontal lobe. Magnetic resonance angiography indicated diffuse cerebrovascular stenosis. Considering these findings to be caused by vasospasm, we started the treatment used for vasospasm secondary to aneurysmal subarachnoid hemorrhage. Magnetic resonance angiography on the 13th postoperative day revealed an improvement in the cerebrovascular stenosis. In this case, it appears that the cause of vasospasm was intraoperative spillage of the contents of the cyst. CONCLUSIONS: Although the occurrence of diffuse cerebral vasospasm after the removal of brain tumors in the posterior fossa is rare, this complication should be noted as a potential postoperative complication after tumor removal; this should lead to earlier diagnosis and treatment and a potentially better prognosis.

Sex-specific differences in transcriptomic profiles and cellular characteristics of oligodendrocyte precursor cells.

The susceptibility to neurological and psychiatric disorders reveals sexual dimorphism in the structure and function of human brains. Recent evidence has also demonstrated the sex-related differences in cellular components of the brain, including neurons, microglia, astrocytes, and endothelial cells. Oligodendrocyte precursor cells (OPCs) regulate the neuronal system in various ways and play crucial roles in brain homeostasis beyond their well-known role as a reservoir for mature oligodendrocytes. Although recent studies have shown regional diversities and heterogeneities of OPCs, sex-related differences in OPCs are largely unknown. Here, we revealed transcriptomic differences in OPCs isolated from male and female neonatal rat brains. Furthermore, we demonstrated sex-dependent differences in OPCs regarding proliferation, migration, differentiation, tolerance against ischemic stress, energy metabolism, and the ability to regulate the blood-brain barrier integrity.

A rat glioblastoma model with diffuse leptomeningeal gliomatosis induced by intracarotid injection of C6 glioma cells.

OBJECTIVE: A reproducible brain tumor model using experimental animals is required to study biological behavior and develop more potent antineoplastic drugs and effective therapeutic modalities. In this work, we attempted to establish diffuse leptomeningeal gliomatosis in the rat by intracarotid injection of C6 glioma cells. METHODS: Intracarotid injection of 1 x 10(7) C6 glioma cells in Wistar rats was performed to establish a primary diffuse leptomeningeal gliomatosis model. Ki-67 and matrix metalloproteinases (MMPs) immunohistochemistry staining were used to study the biological behavior of the developed tumor. Methodology, physical findings and histopathological features were also discussed. RESULTS: Leptomeningeal gliomas grew in all Wistar rats after the administration of 1 x 10(7) C6 glioma cells. Intracranial hypertension, weight loss and cachexia developed, and the median survival time was 18.0 +/- 2.9 days. The glioma mass distributed throughout the ventricles, the leptomeningeal regions in the brain and the brainstem, with typical pathological features of glioblastoma. The immunohistochemistry stainings showed high Ki-67 labeling index (42.1 +/- 10.3%), and concomitant overexpression of MMP-2 and MMP-9 suggested proliferation, invasion and angiogenesis potential. DISCUSSION: The advantage of the intracarotid injection route is the absence of an operative scar in the cranium. This established animal model is a novel model of primary diffuse leptomeningeal gliomatosis. This model probably can be used for pre-clinical testing in the progression of glioblastoma.

High-performance self-expanding stent graft: development and application to experimental aneurysms.

Large or giant aneurysms in the craniocervical area with broad necks are of concern and are treated surgically, endovascularly, or in both ways. Surgically, their treatment is difficult, with relatively high risks. For their embolization, we have been developing a high-performance stent graft that has three characteristics: a thin and expandable segmented polyurethane (SPU) membrane, micropores formed by the excimer laser ablation technique, and a drug delivery system at the membrane. Stent grafts were fabricated using commercially available self-expanding stents. These stents were covered with a thin SPU membrane by the dip-coating method. Micropores were then formed by the excimer laser ablation technique and an argatroban coating was added. We tested the effectiveness of this new stent graft by treating experimental canine aneurysms. Experimental aneurysms were made in the bilateral carotid arteries of four female beagles by end-to-side anastomosis using an autologous venous pouch. One month after aneurysm formation, the experimental aneurysm in one of the carotid arteries was covered with our self-expanding stent graft and the aneurysm in the other artery was covered with a bare self-expanding stent. On angiograms 1 month after stenting, the aneurysms treated with our stent graft were completely occluded without significant parent artery stenosis, but the aneurysms treated with the original bare stent were still open. Our high-performance self-expanding stent graft was easily applied to the experimental aneurysms and accomplished complete occlusion of aneurysms in beagles. Further study should be performed for the goal of clinical use.