Enhanced Stereocomplex Crystallization of Biodegradable Enantiomeric Poly(lactic acid)s by Repeated Casting

Stereocomplex crystallization between PLLA and PDLA is known to be disturbed when their molecular weights increase to >10⁵ g · mol^?1. Here, solution casting of PLLA and PDLA with different solvents was performed repeatedly to increase the time for the PLLA/PDLA solution in the concentration range in which only stereocomplex crystallites are formed and thus to elevate the stereocomplex crystallinity in the materials. The results of WAXS and DSC show that for all solvents examined the crystallinities of stereocomplex crystallites and homocrystallites increased and decreased, respectively, with increasing number of castings, indicating that repeated casting is a promising method to enhance stereocomplex crystallization.

     

Intestinal Permeability Is a Mechanical Rheostat in the Pathogenesis of Liver Cirrhosis

Recent studies have suggested that an alteration in the gut microbiota and their products, particularly endotoxins derived from Gram-negative bacteria, may play a major role in the pathogenesis of liver diseases. Gut dysbiosis caused by a high-fat diet and alcohol consumption induces increased intestinal permeability, which means higher translocation of bacteria and their products and components, including endotoxins, the so-called “leaky gut”. Clinical studies have found that plasma endotoxin levels are elevated in patients with chronic liver diseases, including alcoholic liver disease and nonalcoholic liver disease. A decrease in commensal nonpathogenic bacteria including Ruminococaceae and Lactobacillus and an overgrowth of pathogenic bacteria such as Bacteroidaceae and Enterobacteriaceae are observed in cirrhotic patients. The decreased diversity of the gut microbiota in cirrhotic patients before liver transplantation is also related to a higher incidence of post-transplant infections and cognitive impairment. The exposure to endotoxins activates macrophages via Toll-like receptor 4 (TLR4), leading to a greater production of proinflammatory cytokines and chemokines including tumor necrosis factor-alpha, interleukin (IL)-6, and IL-8, which play key roles in the progression of liver diseases. TLR4 is a major receptor activated by the binding of endotoxins in macrophages, and its downstream signal induces proinflammatory cytokines. The expression of TLR4 is also observed in nonimmune cells in the liver, such as hepatic stellate cells, which play a crucial role in the progression of liver fibrosis that develops into hepatocarcinogenesis, suggesting the importance of the interaction between endotoxemia and TLR4 signaling as a target for preventing liver disease progression. In this review, we summarize the findings for the role of gut-derived endotoxemia underlying the progression of liver pathogenesis.     

Isothermal crystallization and spherulite growth behavior of stereo multiblock poly(lactic acid)s: Effects of block length

Stereo multiblock poly(lactic acid)s (PLA)s and stereo diblock poly(lactic acid) (DB) with a wide variety of block length of 15.4–61.9 lactyl units are synthesized, and the effects of block length sequence on crystallization and spherulite growth behavior are investigated at different crystallization temperatures, in comparison with neat poly(L ‐lactide) (PLLA), poly(D ‐lactide) (PDLA), and PLLA/PDLA blend. Only stereocomplex crystallites as crystalline species are formed in the stereo multiblock PLAs and DB, irrespective of block length and crystallization temperature. The maximum crystallinities (33–61%), maximum radial growth rate of spherulites (0.7–56.7 μm min^?1), and equilibrium melting temperatures (182.0–216.5°C) increased with increasing block length but are less than those of PLLA/PDLA blend (67 %, 122.5 μm min^?1, and 246.0°C). The spherulite growth rates and overall crystallization rates of the stereo multiblock PLAs and DB increased with increasing block length and are lower than that of PLLA/PDLA blend. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Noninvasive quantification of iodine-123-iomazenil SPECT

The feasibility of a noninvasive method for quantification of [123I]iomazenil binding using a standardized arterial input function and a single venous blood sample was assessed in normal volunteers. METHODS: Serial SPECT images and blood data from six healthy male volunteers after intravenous injection of [123I]iomazenil were used. The standardized input function was derived by averaging the six subjects' arterial curves. Individual input functions were estimated by calibrating the standardized input function with one-point venous blood radioactivity concentration. Ligand transport (K1) and receptor binding were computed from the estimated input functions and two separate SPECT scans using a table look-up procedure based on a three-compartment, two-parameter model. Reference values for K1 and receptor binding were determined from the serial SPECT data and individual arterial curves using a three-compartment, three-parameter model and curve fitting. RESULTS: Analyses of the error caused by the calibration in relation to the time postinjection revealed that the optimal calibration time was 30 min postinjection. Receptor binding obtained by this simplified method correlated well with the reference values (r = 0.941) and was estimated within an error of 10% in the cerebral cortical regions. Although the estimated K1 showed relatively poor correlation (r = 0.699) with the reference value, it was an excellent relative measure in each subject. CONCLUSION: Our method provided an absolute measure of the benzodiazepine receptor binding and a relative measure of ligand transport from two SPECT scans and a venous blood sample. This method would be useful for quantitative assessment of benzodiazepine receptors in clinical settings.     

Combination of serine protease inhibitor FUT-175 and thromboxane synthetase inhibitor OKY-046 decreases cerebral vasospasm in patients with subarachnoid hemorrhage

The preventive effect of the serine protease inhibitor FUT-175 (nafamostat mesilate), a potent inhibitor of the complement system, against vasospasm was evaluated in 34 high risk patients with thick and diffuse subarachnoid hemorrhage (SAH) demonstrated by computed tomography corresponding to Fisher group 3. All patients underwent surgery within 96 hours following SAH and received the thromboxane A2 synthetase inhibitor, OKY-046, as part of standard care. FUT-175 (40-160 mg/day) was administered during the initial 4 days following surgery. 455 patients treated without FUT-175 in the Nagasaki SAH Data Bank (non-FUT group) formed the control group. FUT-175 significantly decreased the incidence of symptomatic vasospasm in patients with severe neurological grade (Hunt and Hess grade 3, p < 0.02; Hunt and Hess grade 4, p < 0.02). The incidence of favorable outcome was 76.5% in the FUT group and 60.4% in the non-FUT group, but not statistically different. However, when patients of Hunt and Hess grade 5 were excluded, the FUT group had a significantly improved outcome (p < 0.05). This study suggests that FUT-175 has an additive effect to OKY-046 in preventing vasospasm in high risk patients with severe SAH.     

Activation patterns of covert word generation detected by fMRI: comparison with 3D PET

PURPOSE: The aim of our study was to compare the activation patterns of higher cognitive function detected by functional MRI (fMRI) with those by H2(15)O positron emission tomography (PET). METHOD: Activation studies with both modalities were performed in six normal volunteers with identical covert word generation tasks and statistical analysis. For PET, each subject had five rest scans and five task scans at 10 min intervals. fMRI was performed with a 1.5 T magnet using T2*-weighted echo planar sequences. Each scanning session consisted of two rest and two task periods of 30 s each, alternating rest and task. RESULTS: In group analysis, the activation patterns on both PET and fMRI were similar, whereas the deactivation patterns differed, presumably due to the noise of fMRI. In single-subject analysis, PET showed fewer activated areas and fMRI showed more areas of activation than in group analysis. CONCLUSION: fMRI has an advantage over 3D PET in its better signal-to-noise ratio for detecting change in neuronal activity for higher brain function.     

Regional cerebral blood flow changes in human brain related to ipsilateral and contralateral complex hand movements--a PET study

The purpose of this study was to investigate the cortical motor areas activated in relation to unilateral complex hand movements of either hand, and the motor area related to motor skill learning. Regional cerebral blood flow (rCBF) was measured in eight right-handed healthy male volunteers using positron emission tomography during a two-ball-rotation task using the right hand, the same task using the left hand and two control tasks. In the two-ball-rotation tasks, subjects were required to rotate the same two iron balls either with the right or left hand. In the control task, they were required to hold two balls in each hand without movement. The primary motor area, premotor area and cerebellum were activated bilaterally with each unilateral hand movement. In contrast, the supplementary motor area proper was activated only by contralateral hand movements. In addition, we found a positive correlation between the rCBF to the premotor area and the degree of improvement in skill during motor task training. The results indicate that complex hand movements are organized bilaterally in the primary motor areas, premotor areas and cerebellum, that functional asymmetry in the motor cortices is not evident during complex finger movements, and that the premotor area may play an important role in motor skill learning.     

A Single-Chip MPEG/Audio Decoder LSI Based on a Compact Decoding Algorithm

A single-chip decoder LSI is developed for ISO/IEC MPEG (the International Organisation for Standardisation/the International Electrotechnical Commission, Moving Pictures Expert Group) audio. The applicable layers are Layer I and II of MPEG-1 and MPEG-2/Lower-Sampling-Frequency Mode. A fast calculation algorithm, which is also effective for on-chip memory reduction, is incorporated in audio signal synthesis. The reliability in bitstream synchronization is improved by including bitstream inconsistency detection. Bitstream error concealment by repeating previous audio data is supported. The decoding delay is adjustable when an optional external memory is connected to the LSI.