[Show abstract][Hide abstract] ABSTRACT: Insufficient mechanical properties are one of the major obstacles for the commercialization of ultrahigh permeability thermally rearranged (TR) membranes in large-scale gas separation applications. The incorporation of preformed benzoxazole/benzimidazole units into o-hydroxy copolyimide precursors, which themselves subsequently thermally rearrange to form additional benzoxazole units, were prepared for the first time. Using commercially available monomers, mechanically tough membranes prepared from random and block TR poly(benzoxazole-co-imide) copolymers (TR-PBOI) were investigated for gas separation. The effects of the chemical structures, copolymerization modes, and thermal holding time of o-hydroxy copolyimides on the molecular packing and properties, including gas transport, for the resulting TR-PBOI membranes have been examined in detail. After treatment at 400 °C, tough TR-PBOI membranes exhibited tensile strengths of 71.4−113.9 MPa and elongation at break of 5.1−16.1%. Moreover, they presented higher or comparable gas transport performance as compared to those tough/robust TR membranes reported previously. Reported for the first time is a comparative investigation of the copolymerization mode (random or block) on membrane properties. The novel polymer architecture and systematic property studies promote a better understanding of the materials and process development of commercial TR membranes for gas separation applications.
[Show abstract][Hide abstract] ABSTRACT: To develop a pipeline for realistic head models of nonhuman primates (NHPs) for simulations of noninvasive brain stimulation, and use these models together with empirical threshold measurements to demonstrate that the models capture individual anatomical variability.
Based on structural MRI data, we created models of the electric field (E-field) induced by right unilateral (RUL) electroconvulsive therapy (ECT) in four rhesus macaques. Individual motor threshold (MT) was measured with transcranial electric stimulation (TES) administered through the RUL electrodes in the same subjects.
The interindividual anatomical differences resulted in 57% variation in median E-field strength in the brain at fixed stimulus current amplitude. Individualization of the stimulus current by MT reduced the E-field variation in the target motor area by 27%. There was significant correlation between the measured MT and the ratio of simulated electrode current and E-field strength (r2 = 0.95, p = 0.026). Exploratory analysis revealed significant correlations of this ratio with anatomical parameters including of the superior electrode-to-cortex distance, vertex-to-cortex distance, and brain volume (r2 > 0.96, p < 0.02). The neural activation threshold was estimated to be 0.45 ± 0.07 V/cm for 0.2 ms stimulus pulse width.
These results suggest that our individual-specific NHP E-field models appropriately capture individual anatomical variability relevant to the dosing of TES/ECT. These findings are exploratory due to the small number of subjects.
This work can contribute insight in NHP studies of ECT and other brain stimulation interventions, help link the results to clinical studies, and ultimately lead to more rational brain stimulation dosing paradigms.
[Show abstract][Hide abstract] ABSTRACT: The gas sorption behavior of polyimides (PIs) incorporating Tro¨ger׳s base (TB) units was investigated for five representative small gases (H2, N2, O2, CH4, and CO2) by barometric pressure decay methods at 35 °C. Methanol treatment of the PI-TB membranes increased the sorption, diffusion, and permeation of the small gas molecules because of increased interactions between the polymer and gas molecules as well as an increase of the FFV due to dilation of the polymers. Two different solubility determination methods, pressure-decay based and time-lag based methods, were introduced and compared. The gas solubilities of relatively condensable gases such as CO2 and CH4 showed good agreement between the two solubility measurements. Two different dianhydrides (6FDA and BTDA) in the PI-TBs were also introduced to determine their structural contributions to the gas sorption and transport properties. The two PI-TBs showed similar behavior in Henry׳s mode sorption. However, their Langmuir mode sorption demonstrated distinctive behavior, resulting in different gas transport phenomena. Methanol-treated PI-TB membranes exhibited plasticization resistance for CO2 permeation under high CO2 content feed in CO2/CH4 mixture. Incorporating TB units in the PI backbones achieved comparable microporosity and gas permeability results especially for CO2 separation in highly permeable polymer membranes.
[Show abstract][Hide abstract] ABSTRACT: This study aims to visualize the subjective symptoms before and after the treatment of whiplash injury using infrared (IR) thermography.
IR thermography was performed for 42 patients who were diagnosed with whiplash injury. There were 19 male and 23 female patients. The mean age was 43.12 years. Thermal differences (ΔT) in the neck and shoulder and changes in the thermal differences (ΔdT) before and after treatment were analyzed. Pain after injury was evaluated using visual analogue scale (VAS) before and after treatment (ΔVAS). The correlations between ΔdT and ΔVAS results before and after the treatment were examined. We used Digital Infrared Thermal Imaging equipment of Dorex company for IR thermography.
The skin temperature of the neck and shoulder immediately after injury showed 1-2℃ hyperthermia than normal. After two weeks, the skin temperature was normal range. ΔT after immediately injuy was higher than normal value, but it was gradually near the normal value after two weeks. ΔdT before and after treatment were statistically significant (p<0.05). VAS of the neck and shoulder significantly reduced after 2 week (p=0.001). Also, there was significant correlation between ΔdT and reduced ΔVAS (the neck; r=0.412, p<0.007) (the shoulder; r=0.648, p<0.000).
The skin temperature of sites with whiplash injury is immediately hyperthermia and gradually decreased after two weeks, finally it got close to normal temperature. These were highly correlated with reduced VAS. IR thermography can be a reliable tool to visualize the symptoms of whiplash injury and the effectiveness of treatment in clinical settings.
Journal of Korean Neurosurgical Society 04/2015; 57(4):283-8. DOI:10.3340/jkns.2015.57.4.283 · 0.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A 49-year-old female patient was admitted due to memory disturbances. Magnetic resonance (MR) imaging suggested gliomatosis cerebri (GC), which had spread to both insular lobes, both frontal and basal ganglia and the brain stem. A stereotactic biopsy was performed at the high signal intensity area of the T2-weighted MR image, and the revealed a diffuse astrocytoma. Radiation therapy was judged not to be an appropriate treatment for the patient because of her cognitive impairment. A combinatorial chemotherapy regiment consisting of Procarbazine, CCNU, and Vincristine (PCV) was agreed upon after discussion. The patient underwent six cycles of PCV chemotherapy (a full dose was applied until the 3rd cycle, and dose then was reduced to 75% for the remaining cycles). Although the patient exhibited side effects such as bone marrow suppression and gastrointestinal symptoms, these were managed by medication. Over the 28 months following initiation of treatment, the high signal area in the right frontal and temporal lobes in the T2-weighted MR image decreased, and the patient's cognitive function [global deterioration scale (GDS) 4 points, mini-mental state examination (MMSE) 25 point] also improved (GDS 1 points, MMSE 29 points). PCV chemotherapy can therefore be an alternative therapeutic option for patients with GC who cannot be treated with radiation therapy or other chemotherapies.
[Show abstract][Hide abstract] ABSTRACT: Background:
Despite the promise shown by stem cells for restoration of cardiac function after myocardial infarction, the poor survival of transplanted cells has been a major issue. Hypoxia-inducible factor-1 (HIF1) is a transcription factor that mediates adaptive responses to ischemia. Here, we hypothesize that codelivery of cardiac progenitor cells (CPCs) with a nonviral minicircle plasmid carrying HIF1 (MC-HIF1) into the ischemic myocardium can improve the survival of transplanted CPCs.
Methods and results:
After myocardial infarction, CPCs were codelivered intramyocardially into adult NOD/SCID mice with saline, MC-green fluorescent protein, or MC-HIF1 versus MC-HIF1 alone (n=10 per group). Bioluminescence imaging demonstrated better survival when CPCs were codelivered with MC-HIF1. Importantly, echocardiography showed mice injected with CPCs+MC-HIF1 had the highest ejection fraction 6 weeks after myocardial infarction (57.1±2.6%; P=0.002) followed by MC-HIF1 alone (48.5±2.6%; P=0.04), with no significant protection for CPCs+MC-green fluorescent protein (44.8±3.3%; P=NS) when compared with saline control (38.7±3.2%). In vitro mechanistic studies confirmed that cardiac endothelial cells produced exosomes that were actively internalized by recipient CPCs. Exosomes purified from endothelial cells overexpressing HIF1 had higher contents of miR-126 and miR-210. These microRNAs activated prosurvival kinases and induced a glycolytic switch in recipient CPCs, giving them increased tolerance when subjected to in vitro hypoxic stress. Inhibiting both of these miRs blocked the protective effects of the exosomes.
In summary, HIF1 can be used to modulate the host microenvironment for improving survival of transplanted cells. The exosomal transfer of miRs from host cells to transplanted cells represents a unique mechanism that can be potentially targeted for improving survival of transplanted cells.
[Show abstract][Hide abstract] ABSTRACT: Primary leptomeningeal lymphoma is very rare disease that is a subtype of primary central nervous system (CNS) lymphoma. Primary dural lymphoma is a subentity of primary leptomeningeal lymphoma and arises from the dura mater without systemic disease. A 47-year-old woman presented with an indolent mass in the right frontal region. The patient's physical examination demonstrated no focal neurological abnormality. Magnetic resonance imaging (MRI) study revealed a mass lesion in the right frontal region. The patient underwent a right frontal craniectomy and removal of tumor. Histological diagnosis was diffuse large B-cell lymphoma (DLBCL). The patient received chemotherapy with rituximab, cyclophosphamide, adriamycin, vincristine, and prednisolone (R-CHOP protocol) every 3 weeks for six cycles. The patient was discharged without neurological deficit and no evidence of tumor recurrence. There was no systemic dissemination of disease 72 months after the surgery. Until the optimal standard management protocol is established, the treatment should be with an individualized multidisciplinary approach and continued follow-up and clinical surveillance are recommended for every patient.
[Show abstract][Hide abstract] ABSTRACT: Mouse models are widely used in studies of various forms of transcranial electric stimulation (TES). However, there is limited knowledge of the electric field distribution induced by TES in mice, and computational models to estimate this distribution are lacking. This study examines the electric field and current density distribution in the mouse brain induced by TES. We created a high-resolution finite element mouse model incorporating ear clip electrodes commonly used in mouse TES to study, for example, electroconvulsive therapy (ECT). The electric field strength and current density induced by an ear clip electrode configuration were computed in the anatomically realistic, inhomogenous mouse model. The results show that the median electric field strength induced in the brain at 1 mA of stimulus current is 5.57 V/m, and the strongest field of 20.19 V/m was observed in the cerebellum. Therefore, to match the median electric field in human ECT at 800 mA current, the electrode current in mouse should be set to approximately 15 mA. However, the location of the strongest electric field in posterior brain regions in the mouse does not model well human ECT which targets more frontal regions. Therefore, the ear clip electrode configuration may not be a good model of human ECT. Using high-resolution realistic models for simulating TES in mice may guide the establishment of appropriate stimulation parameters for future in vivo studies.
[Show abstract][Hide abstract] ABSTRACT: Rodent models are valuable for preclinical examination of novel therapeutic techniques, including transcranial magnetic stimulation (TMS). However, comparison of TMS effects in rodents and humans is confounded by inaccurate scaling of the spatial extent of the induced electric field in rodents. The electric field is substantially less focal in rodent models of TMS due to the technical restrictions of making very small coils that can handle the currents required for TMS. We examine the electric field distributions generated by various electrode configurations of electric stimulation in an inhomogeneous high-resolution finite element mouse model, and show that the electric field distributions produced by human TMS can be approximated by electric stimulation in mouse. Based on these results and the limits of magnetic stimulation in mice, we argue that the most practical and accurate way to model focal TMS in mice is electric stimulation through either cortical surface electrodes or electrodes implanted halfway through the mouse cranium. This approach could allow much more accurate approximation of the human TMS electric field focality and strength than that offered by TMS in mouse, enabling, for example, focal targeting of specific cortical regions, which is common in human TMS paradigms.
[Show abstract][Hide abstract] ABSTRACT: This study examines the characteristics of the electric field (E-field) induced in the brain by electroconvulsive therapy (ECT) and magnetic seizure therapy (MST). The electric field induced by five ECT electrode configurations (bilateral, bifrontal, right unilateral, focal electrically administered seizure therapy, and frontomedial) as well as an MST coil configuration (circular) was computed in an anatomically realistic finite element model of the human head. We computed the maps of the electric field strength relative to an estimated neural activation threshold, and used them to evaluate the stimulation strength and focality of the various ECT and MST paradigms. The results show that the median ECT stimulation strength in the brain is 3-11 times higher than that for MST, and that the stimulated brain volume is substantially higher with ECT (47-100%) than with MST (21%). Our study provides insight into the observed reduction of cognitive side effects in MST compared to ECT, and supports arguments for lowering ECT current amplitude as a means of curbing its side effects.
[Show abstract][Hide abstract] ABSTRACT: Aims:
Hypoxia-inducible factor-1 (HIF-1) has been reported to promote tolerance against acute myocardial ischaemia-reperfusion injury (IRI). However, the mechanism through which HIF-1 stabilization actually confers this cardioprotection is not clear. We investigated whether HIF-1α stabilization protects the heart against acute IRI by preventing the opening of the mitochondrial permeability transition pore (MPTP) and the potential mechanisms involved.
Methods and results:
Stabilization of myocardial HIF-1 was achieved by pharmacological inhibition of prolyl hydroxylase (PHD) domain-containing enzyme using GSK360A or using cardiac-specific ablation of von Hippel-Lindau protein (VHL(fl/fl)) in mice. Treatment of HL-1 cardiac cells with GSK360A stabilized HIF-1, increased the expression of HIF-1 target genes pyruvate dehydrogenase kinase-1 (PDK1) and hexokinase II (HKII), and reprogrammed cell metabolism to aerobic glycolysis, thereby resulting in the production of less mitochondrial oxidative stress during IRI, and less MPTP opening, effects which were shown to be dependent on HKII. These findings were further confirmed when HIF-1 stabilization in the rat and murine heart resulted in smaller myocardial infarct sizes (both in vivo and ex vivo), decreased mitochondrial oxidative stress, and inhibited MPTP opening following IRI, effects which were also found to be dependent on HKII.
We have demonstrated that acute HIF-1α stabilization using either a pharmacological or genetic approach protected the heart against acute IRI by promoting aerobic glycolysis, decreasing mitochondrial oxidative stress, activating HKII, and inhibiting MPTP opening.
Cardiovascular Research 07/2014; 104(1). DOI:10.1093/cvr/cvu172 · 5.94 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this article, we propose an automatic cloud detection process for images with high spatial resolution. First, thick cloud regions are detected by applying a simple threshold method to the target image (an image that includes a cloud-covered region). Next, a reference image (another image that was acquired at a different time and includes the region with relatively little or no cloud-cover) is transformed to the coordinates of the target image by a modified scale-invariant feature transform (SIFT) method. The difference between the target image and transformed reference image is used to extract the peripheral cloud regions. The thick and peripheral cloud regions are then merged based on their relative locations and areas to detect the final cloud regions. Multi-temporal Korea Multi-Purpose Satellite-2 (KOMPSAT-2) images are used to construct study sites to evaluate the proposed method for a range of cloud-cover cases. From the proposed method, a large number of correctly matched points were extracted for this generation of the transformation model, and cloud-covered regions were effectively detected for all sites without manual intervention.