Influence of Smectic Liquid Crystallinity on Lamellar Microdomain Structure in a Main‐Chain Liquid Crystal Block Copolymer Fiber

The microlamellar and smectic liquid crystal (LC) structures of a block copolymer of a main‐chain LC polyester connected at both ends with poly(ethyl methacrylate) are investigated by fiber X‐ray scattering. In the as‐spun fiber, the lamellae are parallel to the fiber axis, while the smectic layers are perpendicular to it. Annealing the as‐spun fiber at a temperature higher than the isotropization temperature (T_i) of the LC segment preserves the lamellae, but the LC structure disappears. Further annealing the fiber at T < T_i improves the lamellar stacking coherence and aligns the smectic layers parallel to the lamellae. In contrast, annealing the as‐spun fiber at T < T_i conserves the smectic layers and arranges the lamellae in parallel to the smectic layers. Thus, the liquid crystallinity affects the lamellar ordering and orientation.

     

Effect of photo-thermal acceleration on in-office bleaching

Odontology - The purpose is to evaluate the effect of photo-thermal acceleration on in-office bleaching efficiency using a bleaching agent without photocatalysts in vitro. Artificially discolored...     

Mechanical properties of nerve roots and rami radiculares isolated from fresh pig spinal cords

No reports have described experiments designed to determine the strength characteristics of spinal nerve roots and rami radiculares for the purpose of explaining the complexity of symptoms of medullary cone lesions and cauda equina syndrome. In this study, to explain the pathogenesis of cauda equina syndrome, monoaxial tensile tests were performed to determine the strength characteristics of spinal nerve roots and rami radiculares, and analysis was conducted to evaluate the stress-strain relationship and strength characteristics. Using the same tensile test device, the nerve root and ramus radiculares isolated from the spinal cords of pigs were subjected to the tensile test and stress relaxation test at load strain rates of 0.1, 1, 10, and 100 s^-1 under identical settings. The tensile strength of the nerve root was not rate dependent, while the ramus radiculares tensile strength tended to decrease as the strain rate increased. These findings provide important insights into cauda equina symptoms, radiculopathy, and clinical symptoms of the medullary cone.     

Mechanisms of acute gain and late lumen loss after atherectomy in different preintervention arterial remodeling patterns

The main mechanism of restenosis after directional coronary atherectomy (DCA) remains obscure. We investigated mechanisms of restenosis after DCA in different coronary artery remodeling patterns. DCA was performed in 51 de novo lesions. The lesions were evaluated by intravascular ultrasound (IVUS) before, immediately after, and 6 months after the procedure. According to the IVUS findings before DCA, we classified the lesions into the following 3 groups: (1) positive (n = 10), (2) intermediate (n = 25), and (3) negative (n = 16) remodeling. We measured lumen area, vessel area, and plaque area using IVUS before DCA, immediately after DCA, and at follow-up. Lumen area increase after DCA was mainly due to plaque area reduction in the positive and intermediate remodeling groups (90 plus minus 15% and 80 plus minus 25% increase in lumen area, respectively), whereas that in the negative remodeling group was due to both plaque area reduction (57 plus minus 22% increase in lumen area) and vessel area enlargement (43 plus minus 33% increase in lumen area). The plaque area increase correlated strongly with late lumen area loss in the positive and intermediate remodeling groups (r = 0.884, p <0.001; r = 0.626, p <0.001, respectively), but the decrease in vessel area was not correlated with lumen area loss. In contrast, both an increase in plaque area and a decrease in vessel area were correlated with late lumen area loss (r = 0.632, p = 0.009; r = 0.515, p = 0.041) in the negative remodeling group. Coronary artery restenosis after atherectomy was primarily due to an increase in plaque in the positive and/or intermediate remodeling groups. However, in the negative remodeling group, late lumen loss might have been caused by both an increase in plaque and vessel shrinkage.     

Quantifying and visualizing weak interactions between anions and proteins

The molecular properties of proteins are influenced by various ions present in the same solution. While site-specific strong interactions between multivalent metal ions and proteins are well characterized, the behavior of other ions that are only weakly interacting with proteins remains elusive. In the current study, using NMR spectroscopy, we have investigated anion–protein interactions for three proteins that are similar in size but differ in overall charge. Using a unique NMR-based approach, we quantified anions accumulated around the proteins. The determined numbers of anions that are electrostatically attracted to the charged proteins were notably smaller than the overall charge valences and were consistent with predictions from the Poisson–Boltzmann theory. This NMR-based approach also allowed us to measure ionic diffusion and characterize the anions interacting with the positively charged proteins. Our data show that these anions rapidly diffuse while bound to the proteins. Using the same experimental approach, we observed the release of the anions from the protein surface upon the formation of the Antp homeodomain–DNA complex. Using paramagnetic relaxation enhancement (PRE), we visualized the spatial distribution of anions around the free proteins and the Antp homeodomain–DNA complex. The obtained PRE data revealed the localization of anions in the vicinity of the highly positively charged regions of the free Antp homeodomain and provided further evidence of the release of anions from the protein surface upon the protein–DNA association. This study sheds light on the dynamic behavior of anions that electrostatically interact with proteins.

Biological systems involve various inorganic and organic ions. Protein functions are influenced by the surrounding ions not only through the electrostatic screening effect (1), but also through direct interactions at the molecular surfaces (2). Compared to typical protein–ligand interactions, protein–ion interactions are weaker and more transient, yet ions can significantly influence various properties such as solubility, stability, and functional activities of proteins (3). The influences depend on ionic species. For example, when Cl⁻ ions are replaced with glutamate ions in biochemical experiments, some DNA-binding proteins exhibit substantially stronger (>100-fold for some cases) affinity for DNA (4, 5). To understand how ions affect the molecular properties of proteins, the behavior of ions around proteins should be elucidated.For DNA and RNA, ion-counting methods have greatly advanced experiment-based knowledge of ionic interactions (6, 7). These methods were successfully used to examine and validate theoretical models for ion–nucleic acid interactions (8, 9). However, ion-counting methods do not provide any information about the spatial distribution and dynamic properties of counterions around macromolecules. Even at high resolution in crystal structures, the vast majority of counterions are unresolved, suggesting that they are highly mobile. The dynamic nature of ions causes a major difficulty in studying the interactions between ions and biological macromolecules.Weak transient interactions of monovalent ions with proteins are particularly difficult to capture by experiments. Unlike nucleic acids that possess a negative charge at every residue, proteins typically contain both positively charged and negatively charged residues as well as many neutral residues. Consequently, proteins possess a far smaller overall charge than nucleic acids of similar molecular size. This implies that the electrostatic attraction of ions to proteins could be intrinsically weaker than that to nucleic acids. Furthermore, local environments around individual charged moieties of proteins are more diverse compared to those of nucleic acids. Although NMR spectroscopy is powerful for investigating various physicochemical properties of proteins (10, 11), there has been a lack of methods suited to quantitatively investigate ion–protein interactions. Experimental studies of weak ion–protein interactions have been challenging (3).In this work, using unique experimental methods, we study how anions behave in the vicinity of proteins. Our NMR-based approach allows us to determine how many anions are attracted to proteins. Our data show that the number is significantly smaller than the overall charge valence of each positively charged protein. We explain this observation using the concept of the ion atmosphere and theoretical calculations based on the Poisson–Boltzmann equation. Our experimental approach also reveals the diffusional properties of anions interacting with proteins and unravels the release of anions from the protein surface upon protein–DNA association. Furthermore, our solvent paramagnetic relaxation enhancement (PRE) data show how anions are spatially distributed around the protein surface and how their distribution changes when the protein binds to DNA. Our study sheds light on the dynamic behavior of counterions around proteins.     

A case of tooth autotransplantation after long-term cryopreservation using a programmed freezer with a magnetic field

This case report describes the treatment of a skeletal Class III malocclusion with autotransplantation of a cryopreserved tooth. To gain an esthetic facial profile and good occlusion, extraction of bimaxillary premolars and surgical therapy were chosen. The patient had chronic apical periodontitis on the lower left first molar. Although she did not feel any pain in that region, the tooth was considered to have a poor prognosis. Therefore, we cryopreserved the extracted premolars to prepare for autotransplantation in the lower first molar area because the tooth would probably need to be removed in the future. The teeth were frozen by a programmed freezer with a magnetic field (CAS freezer) that was developed for tissue cryopreservation and were cryopreserved in −150°C deep freezer. After 1.5 years of presurgical orthodontic treatment, bilateral sagittal split ramus osteotomy was performed for mandible setback. Improvement of the facial profile and the occlusion were achieved in the retention phase. Six years after the initial visit, the patient had pain on the lower left first molar, and discharge of pus was observed, so we extracted the lower left first molar and autotransplanted the cryopreserved premolar. Three years later, healthy periodontium was observed at the autotransplanted tooth. This case report suggests that long-term cryopreservation of teeth by a CAS freezer is useful for later autotransplantation, and this can be a viable technique to replace missing teeth.     

Effect of paralyzed side soleus muscle pressure on the gait of stroke patients as measured by a three-dimensional motion analysis system

[Purpose] The purpose of this study was to examine the effects of muscle belly compression by a supporter on the paralyzed side soleus muscle of patients with cerebrovascular disability, and to determine the intensity of compression that is effective for improving gait. [Subjects] Eleven patients with chronic cerebral vascular disorder. [Methods] Before setting the supporter, standing posture and 6 m free walking were measured 3 times with the three-dimensional motion analysis system, VICON. Then, supporters were placed on the center of the lower leg of the hemiplegic side of the subjects and inflated to 30 or 50 mmHg. Three minutes after wearing the supporters, the subjects walked again for 3 times. The data measured with VICON were processed using Visial3D.V4, and the angles of the ankle, steps of the hemiplegic and non-hemiplegic sides, walking speed, walk rate and cadence were calculated. [Results] Compared to without a supporter, a supporter with 30 mmHg pressure showed a significant reduction in the angle of the knee at Initial Contact (IC), and a significant increase in the power of the knee extension at Loading Response (LR). [Conclusion] The results reveal a supporter with that of the subjects during pressure over 30 mmHg applied for 3 minutes improved the knee angle power and hemiplegia walking.Key words: Cerebrovascular disabilities, Pressure, Walking