RESUMO
Peyer's patches (PPs), which contain an abundance of B and T cells, play a key role in inducing pivotal immune responses in the intestinal tract. PPs are defined as aggregated lymph follicles, which consist of multiple lymph follicles (LFs) that may interact with each other in a synergistic manner. LFs are thought to be spherical in shape; however, the characteristics of their structure are not fully understood. To elucidate changes in the structure of PPs as individuals grow, we generated serial 2D sections from entire PPs harvested from mice at 2, 4, and 10 weeks of age and performed a 3D analysis using a software, Amira. Although the number of LFs in PPs was not changed throughout the experiment, the volume and surface area of LFs increased significantly, indicating that LFs in PPs develop continuously by recruiting immune cells, even after weaning. In response to the dramatic changes in the intestinal environment after weaning, the development of germinal centers (GCs) in LFs was observed at 4 and 10 weeks (but not 2 weeks) of age. In addition, GCs gradually began to form away from the center of LFs and close to the muscle layer where export lymphatic vessels develop. Importantly, each LF was joined to the adjacent LF; this feature was observed even in preweaning nonactivated PPs. These results suggest that PPs may have a unique organization and structure that enhance immune functions, allowing cells in LFs to have free access to adjacent LFs and egress smoothly from PPs to the periphery upon stimulation after weaning.
Assuntos
Nódulos Linfáticos Agregados , Desmame , Animais , Nódulos Linfáticos Agregados/imunologia , Camundongos , Centro Germinativo/imunologia , Linfócitos B/imunologia , Junções IntercelularesRESUMO
Red blood cell-inspired perfluorocarbon-encapsulated core-shell particles have been developed for biomedical applications. Although the use of perfluorodecalin (FDC) is expected for core-shell particles owing to its high oxygen solubility, the low solubility of FDC in any organic solvent, owing to its fluorous properties, prevents its use in core-shell particles. In this study, a new cosolvent system composed of dichloromethane (DCM) and heptafluoropropyl methyl ether (HFPME) was found to dissolve both FDC and fluorinated polyimide (FPI) based on a systematic study using a phase diagram, achieving a homogeneous disperse phase for emulsification composed of oxygen-permeable FPI and oxygen-soluble FDC. Using this novel cosolvent system and Shirasu porous glass (SPG) membrane emulsification, FDC-encapsulated FPI shell microparticles were successfully prepared for the first time. In addition to oxygenation, demonstrated using hypoxia-responsive HeLa cells, the fabricated core-shell microparticles exhibited monodispersity, excellent stability, biocompatibility, and oxygen capacity.
RESUMO
A recombinant L-rhamnose isomerase (L-RhI) from probiotic Lactobacillus rhamnosus Probio-M9 (L. rhamnosus Probio-M9) was expressed. L. rhamnosus Probio-M9 was isolated from human colostrum and identified as a probiotic lactic acid bacterium, which can grow using L-rhamnose. L-RhI is one of the enzymes involved in L-rhamnose metabolism and catalyzes the reversible isomerization between L-rhamnose and L-rhamnulose. Some L-RhIs were reported to catalyze isomerization not only between L-rhamnose and L-rhamnulose but also between D-allulose and D-allose, which are known as rare sugars. Those L-RhIs are attractive enzymes for rare sugar production and have the potential to be further improved by enzyme engineering; however, the known crystal structures of L-RhIs recognizing rare sugars are limited. In addition, the optimum pH levels of most reported L-RhIs are basic rather than neutral, and such a basic condition causes non-enzymatic aldose-ketose isomerization, resulting in unexpected by-products. Herein, we report the crystal structures of L. rhamnosus Probio-M9 L-RhI (LrL-RhI) in complexes with L-rhamnose, D-allulose, and D-allose, which show enzyme activity toward L-rhamnose, D-allulose, and D-allose in acidic conditions, though the activity toward D-allose was low. In the complex with L-rhamnose, L-rhamnopyranose was found in the catalytic site, showing favorable recognition for catalysis. In the complex with D-allulose, D-allulofuranose and ring-opened D-allulose were observed in the catalytic site. However, bound D-allose in the pyranose form was found in the catalytic site of the complex with D-allose, which was unfavorable for recognition, like an inhibition mode. The structure of the complex may explain the low activity toward D-allose. KEY POINTS: ⢠Crystal structures of LrL-RhI in complexes with substrates were determined. ⢠LrL-RhI exhibits enzyme activity toward L-rhamnose, D-allulose, and D-allose. ⢠The LrL-RhI is active in acidic conditions.
Assuntos
Aldose-Cetose Isomerases , Lacticaseibacillus rhamnosus , Humanos , Raios X , Ramnose , MonossacarídeosRESUMO
The copper-zinc superoxide dismutase (CuZnSOD) from lemon (SOD_CL) is active in an acidic environment and resists proteolytic degradation. The enzyme occurs as a dimer, which has an indirect effect on the enzyme activity as the monomer retains only â¼35% of the activity. Here, the crystal structure of SOD_CL at 1.86â Å resolution is reported that may explain this peculiarity. The crystal belonged to space group P21, with unit-cell parameters a = 61.11, b = 74.55, c = 61.69â Å, ß = 106.86°, and contained four molecules in the asymmetric unit. The overall structure of SOD_CL resembles that of CuZnSOD from plants. The structure of SOD_CL shows a unique arrangement of surface loop IV that connects the dimer interface and the active site, which is located away from the dimer-interface region. This arrangement allows direct interaction between the residues residing in the dimer interface and those in the active site. The arrangement also includes Leu62 and Gln164, which are conserved in cytoplasmic CuZnSOD. This supports the classification of SOD_CL as a cytoplasmic CuZnSOD despite sharing the highest amino-acid sequence homology with CuZnSODs from spinach and tomato, which are chloroplastic.
Assuntos
Cobre , Superóxido Dismutase , Superóxido Dismutase/química , Cobre/química , Cobre/metabolismo , Cristalografia por Raios X , Citoplasma , ZincoRESUMO
O efeito anti-hipertensivo e a segurança da terapia a longo prazo com nifedipina foi avaliada em 132 pacientes hipertensos, incluindo 100 pacientes idosos que receberam apenas nifedipina ou nifedipina juntamente com outros agentes anti-hipertensivos durante um período médio de 28,6 meses. Foi observado um pronto efeito anti-hipertensivo um mês após o início da terapia com nifedipina. O efeito anti-hipertensivo persistiu durante todo o período de acompanhamento e estava relacionado ao nível pressórico sangüíneo médio do pré-tratamento. Näo foi observada tolerância tardia à droga. Tonturas, rubor facial e outras sensaçöes desagradáveis foram observadas em 7,5% dos pacientes e edema de tornozelo em 9,8%. A terapêutica näo influenciou significativamente os níveis de creatinina sérica. Hipotensäo e outros efeitos colaterais foram a causa de interrupçäo da terapêutica em 10,6% e 4,5% dos pacientes, respectivamente. Concluiu-se que a terapia anti-hipertensiva a longo prazo com nifedipina é eficaz e segura, näo apenas em pacientes adultos mas também em pacientes idosos de alto risco