Feasibility of Mechanical Thrombectomy for Acute Ischemic Stroke Patients Aged 90 Years or Older Compared to Younger Patients.

Mechanical thrombectomy (MT) is a proven treatment for acute ischemic stroke (AIS). However, the efficacy of this treatment is uncertain for very elderly patients. This study aimed to investigate the safety and effectiveness of MT in 90 years or older patients compared with younger patients. We retrospectively reviewed AIS patients treated with MT between October 2018 and June 2020 in our institution. Patients were divided into two groups: aged ≥90 and <90 years. We compared the following factors: functional outcome at discharge, in-hospital death, successful recanalization, and complications. Multivariate logistic regression analysis for the good functional outcome was performed. In consideration of pre-stroke basic activities of very elderly patients, we defined the good functional outcome as modified Rankin Scale (mRS) 0-3. In all, 66 patients were included, and 19 patients (28%) were ≥90 years old. Pre-stoke mRS was higher in ≥90-year-old patients (p = 0.01). In ≥90-year-old patients, we achieved successful recanalization in 17 patients (90%), and only one patient experienced hemorrhagic complication related with the procedure. The good functional outcome (mRS: 0-3) at discharge were six patients (32%) in ≥90 years old versus 19 patients (40%) in <90 years old (p = 0.6). Three patients died in hospital in each group (16% versus 6%) (p = 0.3). Only the stroke severity was negatively related with the good functional outcome in a multivariate analysis. In conclusion, for ≥90-year-old patients compared with younger patients, MT is an equally feasible therapy. Patients should not be excluded from MT based on age alone.

Transient Global Amnesia Following Coil Embolization for a Basilar-tip Aneurysm: Case Reports of Two Patients.

Transient global amnesia (TGA) can be caused by medications, ischemia, metabolic abnormalities, and seizures. We describe two cases of TGA following coil embolization for a basilar-tip aneurysm. A 73-year-old woman developed transient acute anterograde amnesia after coil embolization for a basilar-tip aneurysm. Diffusion-weighted imaging (DWI) revealed an ischemic lesion in the anterior nucleus of the thalamus. A 67-year-old woman developed transient acute amnesia after a stent-assisted coil embolization of a basilar-tip aneurysm. A DWI showed ischemic lesions in the anterior nucleus of the thalamus. Any ischemic changes to areas of the anterior nucleus that are fed by the thalamoperforating and premammillary arteries should be considered in a differential diagnosis for TGA in patients who have undergone coil embolization for a posterior circulation cerebral aneurysm.

The Belousov-Zhabotinsky Reaction in Thermoresponsive Core-Shell Hydrogel Microspheres with a Tris(2,2'-bipyridyl)ruthenium Catalyst in the Core.

The Belousov-Zhabotinsky (BZ) reaction shows temporal or spatiotemporal structures such as redox oscillation of the catalyst, [ruthenium(II)tris(2,2'-bipyridine)][PF6]2 ([Ru(bpy)3][PF6]2). In this study, autonomously oscillating hydrogel microspheres (microgels) were investigated, which show swelling/deswelling oscillation induced by the redox oscillation of the BZ reaction inside the gel. Despite the periodically and autonomously induced oscillation that does not require an external stimulus, it has not been possible to perform any manipulation of the oscillatory behavior over time. The results of the present study show that it is possible to reversibly switch the microgel oscillations from an "on" active state of the BZ reaction to an "off" inactive state by changing the temperature in combination with thermoresponsive microgels. To realize on-demand switching, the construction of double-shell structures is crucial; the thermoresponsive first shell allows the microgels to modulate the diffusion of the substrates or intermediates in the BZ reaction, while the second shell maintains colloidal stability under high temperatures and high ion concentrations. The functionalized double-shell microgels were prepared via multistep seeded precipitation polymerization. The oscillatory switching behavior of the BZ reaction was observed directly and evaluated by ultraviolet-visible (UV-vis) spectroscopy. The central concept of this study, i.e., "on-off switching" can be expected to benefit the development of advanced bioinspired materials.

Protein uptake into individual hydrogel microspheres visualized by high-speed atomic force microscopy.

The moment of protein uptake into hydrogel microspheres (microgels) was directly monitored at the nanoscale by high-speed atomic force microscopy. The dynamic morphological changes in the microgels during protein uptake are largely different depending on the type of protein, and the properties and structure of the microgels, which would affect the colloidal stability of protein-microgel hybrids both in vitro and in vivo.

Non-Thermoresponsive Decanano-sized Domains in Thermoresponsive Hydrogel Microspheres Revealed by Temperature-Controlled High-Speed Atomic Force Microscopy.

Despite the tremendous efforts devoted to the structural analysis of hydrogel microspheres (microgels), many details of their structures remain unclear. Reported in this study is that thermoresponsive poly(N-isopropyl acrylamide) (pNIPAm)-based microgels exhibit not only the widely accepted core-shell structures, but also inhomogeneous decanano-sized non-thermoresponsive spherical domains within their dense cores, which was revealed by temperature-controlled high-speed atomic force microscopy (TC-HS-AFM). Based on a series of experiments, it is concluded that the non-thermoresponsive domains are characteristic for pNIPAm microgels synthesized by precipitation polymerization, and plausible structures for microgels prepared by other polymerization techniques are proposed.

Hydrogel Microellipsoids that Form Robust String-Like Assemblies at the Air/Water Interface.

Soft colloidal particles such as hydrogel microspheres assemble at air/water or oil/water interfaces, where the soft colloids are highly deformed and their surface polymer chains are highly entangled with each other. Herein, we report the formation of robust one-dimensional, string-like colloidal assemblies through self-organization of hydrogel microspheres with shape anisotropy at the air/water interface of sessile droplets. Shape-anisotropic hydrogel microspheres were synthesized via two-step polymerization, whereby a hydrogel shell was formed onto preformed rigid microellipsoids. The shape anisotropy of the hydrogel microspheres was confirmed by transmission electron microscopy and high-speed atomic force microscopy as well as by light-scattering measurements. The present findings are crucial for the understanding of natural self-organization phenomena, where "softness" influences microscopic assembled structures such as those of Nostoc bacteria.

Autonomously Oscillating Hydrogel Microspheres with High-Frequency Swelling/Deswelling and Dispersing/Flocculating Oscillations.

Fast swelling/deswelling and dispersing/flocculating oscillations of autonomously oscillating hydrogel microspheres (microgels) at periods of single-order seconds were accomplished. The design of the oscillating microgels is based on the incorporation of neutral and hydrophilic acrylamide monomers into conventional microgels to suppress the irreversible aggregation of the microgels during oscillation at high substrate concentrations and high temperatures in the Belousov-Zhabotinsky (BZ) reaction. In contrast to conventional microgels, the aforementioned microgels can carry out the BZ reaction under optimized conditions without irreversible aggregation at higher temperature, resulting in short oscillation periods (∼7 s) that were obtained from optical transmittance measurements. Furthermore, a macrogel composed of organized microgels was prepared, which also showed a remarkably fast swelling/deswelling oscillation (oscillation period: ∼23 s). This new type of oscillating microgel could be applied to advanced materials, e.g. to autonomously oscillating micropumps that imitate the human heartbeat.

Self-Organization of Soft Hydrogel Microspheres during the Evaporation of Aqueous Droplets.

The unique drying behavior of aqueous droplets that contain soft hydrogel microspheres (microgels) upon evaporation was systematically investigated. Compared to the ring-shaped deposits that are obtained from drying solid microsphere dispersions, we have previously reported that uniformly ordered thin films are obtained from drying ∼1.2 µm-sized poly( N-isopropyl acrylamide) microgel dispersions. In the present study, we thoroughly investigated several hitherto unexplored aspects of this self-organization, such as the effect of the size, chemical structure, and "softness" of the microgels (or rigid microspheres). For the macro- and microscopic observation of the drying behavior of various microsphere dispersions, an optical microscope and a digital camera were employed. The results suggested that the convection in the aqueous droplets plays an important role for the transportation of the microgels to the air/water interface, where the softness and surface activity of the microgels strongly affects the adsorption of the microgels. On the basis of these discoveries, a design concept for the rapid formation of uniform thin films of soft microgels was proposed.

The deformation of hydrogel microspheres at the air/water interface.

The deformation of soft hydrogel microspheres (microgels) adsorbed at the air/water interface was investigated for the first time using large poly(N-isopropyl acrylamide)-based microgels synthesized by a modified aqueous precipitation polymerization method. The deformation of the micron-sized soft microspheres could be visualized clearly and analyzed quantitatively at the air/water interface.

Monitoring Thermoresponsive Morphological Changes in Individual Hydrogel Microspheres.

Real-time morphology/structure changes in individual hydrogel microspheres (microgels) were directly visualized at high spatiotemporal resolution using high-speed atomic force microscopy (HS-AFM) under temperature control ranging from room temperature to ∼40 °C. The recorded HS-AFM movies demonstrate that the size and morphology of thermoresponsive poly(N-isopropyl acrylamide)-based microgels change with increasing temperature at the individual microgel level. Specifically, the height of the microgels gradually decreases and domain structures appeared even below the volume phase transition temperature. Moreover, the domain structure is retained, even after the microgels have fully collapsed. The present study thus demonstrates that temperature-controlled HS-AFM is a useful tool for monitoring stimulus-responsiveness of microgels. In the near future, it should furthermore be possible to extend this temperature-controlled HS-AFM to other stimulus-responsive materials, including autonomously oscillating microgels.

Fast Adsorption of Soft Hydrogel Microspheres on Solid Surfaces in Aqueous Solution.

The real-time adsorption behavior of polymeric colloidal microspheres onto solid surfaces in aqueous solution was visualized for the first time using high-speed atomic force microscopy (HS-AFM) to reveal how the softness of the microspheres affects their dynamic adsorption. Studies that focus on the deformability of microspheres upon dynamic adsorption have not yet been reported, most likely on account of a lack of techniques that appropriately depict the dynamic adsorption and deformation behavior of individual microspheres at the nanoscale in real time. In this study, the deformability of microspheres plays a crucial role on the adsorption kinetics, that is, soft hydrogel microspheres adsorb faster than harder elastomeric or rigid microspheres. These results should provide insight towards development of new colloidal nanomaterials that exhibit effective adsorption on specific sites in aqueous solution.

Water-immiscible bioinert coatings and film formation from aqueous dispersions of poly(2-methoxyethyl acrylate) microspheres.

Poly(2-methoxyethyl acrylate) (pMEA) microspheres are prepared through facile free-radical polymerization in water without additives and impurities, such as surfactants, other polymers, and organic solvents, which are usually used to synthesize pMEA chains. Clean and pure (non-factionalized and non-cross-linking) pMEA microspheres exhibit plasma-protein adsorption resistances on their surface regardless of their charged state. They are characterized in terms of the adsorbed amounts of proteins at pH 7. In addition, these soft and deformable pMEA microspheres are suitable for forming substrates coated with pMEA microspheres and free-standing films by injecting pMEA dispersion and evaporating the aqueous medium through fusion between the pMEA chains at the surface without the precoating agent and cross-linker. These pMEA coatings have been used till now in artificial heart/lung fabrication and metal products manufacturing by casting organic solvents such as 1,4-dioxane, toluene, and methanol and dissolving pMEA chains prepared using conventional solution polymerization. In this study, bioinert coatings and adhesive and transferable films are easily obtained due to the rubber-like properties of the pMEA microspheres and stable in mild and biocompatible conditions even when these impurities are not used completely, allowing us to provide a guideline for potential pMEA bioapplications such as coatings, films, barriers, and implant devices.

Investigation of Changes in the Microscopic Structure of Anionic Poly(N-isopropylacrylamide-co-Acrylic acid) Microgels in the Presence of Cationic Organic Dyes toward Precisely Controlled Uptake/Release of Low-Molecular-Weight Chemical Compound.

Changes in a microscopic structure of an anionic poly(N-isopropylacrylamide-co-acrylic acid) microgel were investigated using small- and wide-angle X-ray scattering (SWAXS). The scattering profiles of the microgels were analyzed in a wide scattering vector (q) range of 0.07 ≤ q/nm(-1) ≤ 20. In particular, the microscopic structure of the microgel in the presence of a cationic dye rhodamine 6G (R6G) was characterized in terms of its correlation length (ξ), which represents the length scale of the spatial correlation of the network density fluctuations, and characteristic distance (d*), which originated from the local packing of isopropyl groups of two neighboring chains. In the presence of cationic R6G, ξ exhibited a divergent-like behavior, which was not seen in the absence of R6G, and d* was decreased with decreasing the volume of the microgel upon increasing temperature. At the same time, the amount of R6G adsorbed per unit mass of the microgel increased upon heating. These results suggested that a coil-to-globule transition of the poly(N-isopropylacrylamide) chains in the present anionic microgel occurred because of efficiently screened, thus, short ranged electrostatic repulsion between the charged groups, and hydrophobic interaction between the isopropyl groups in the presence of cationic R6G. The combination of hydrophobic and electrostatic interaction between the cationic dye and the microgel affected the separation and volume transition behavior of the microgel.

Small-Angle X-ray Scattering Study on Internal Microscopic Structures of Poly(N-isopropylacrylamide-co-tris(2,2'-bipyridyl))ruthenium(II) Complex Microgels.

Internal microscopic structures of poly(N-isopropylacrylamide-co-tris(2,2'-bipyridyl))ruthenium(II) complex microgels were investigated using small-angle X-ray scattering (SAXS) in the extended q-range of 0.07 ≤ q/nm(-1) ≤ 20. The microgels were prepared by aqueous free-radical precipitation polymerization, resulting in formation of monodispersed, submicrometer-sized microgels, which was confirmed by transmission electron microscopy and dynamic light scattering. To reveal the changes in the microscopic structures of the microgels during swelling/deswelling or dispersing/flocculating oscillation, the redox state of Ru(bpy)3 complexes was fixed in the microgels using Ce(IV) or Ce(III) ions under high ionic strength (1.5 M) during the SAXS measurements. The scattering intensity of the microgels manifested five different structural features. In particular, the correlation length (ξ), which was obtained from the fitting analysis using the Ornstein-Zernike equation, of the microgels both in the reduced and oxidized Ru(bpy)3 states exhibited divergent-like behavior. In addition, a low-q peak centered at q ≈ 5 nm(-1) did not appear clearly in both the reduced [Ru(bpy)3](2+) and oxidized [Ru(bpy)3](3+) states, indicating that the formation of a polymer-rich domain was suppressed; thus, Ru(bpy)3 complexes can be active even though the microgels are deswollen or flocculated during the oscillation reaction.

Ruptured extracranial vertebral artery aneurysm associated with neurofibromatosis type 1. Case report.

A 31-year-old man presented with a ruptured right extracranial vertebral artery aneurysm associated with neurofibromatosis type 1, manifesting as acute onset of right neck and shoulder pain, and right supraclavicular mass. Three-dimensional computed tomography angiography showed a large aneurysm involving the right extracranial vertebral artery associated with a pseudoaneurysm. The aneurysm was successfully treated by transarterial endovascular trapping with detachable coils. Extracranial vertebral artery aneurysm is rare, but the mortality of ruptured cases is extremely high, so early diagnosis and early treatment are important. The present case shows that endovascular treatment was very effective.