Heart valve closure timing intervals in response to left ventricular blood pressure

This article investigates the relationships between heart valve closure timing intervals and left ventricular systolic blood pressure (LVSBP). For this investigation, the cardiopulmonary system is modeled as an analog circuit, including heart chambers, the distal and proximal aorta, distal and proximal systemic arteries/veins, systemic capillaries, the vena cava, the distal and proximal pulmonary artery, distal and proximal pulmonary arteries/veins, pulmonary capillaries and physiological control of heart rate and cardiac contractibility. In this model, the ventricles, atria and arteries were modeled as advanced pressur-volume relationships. A vagal-sympathetic mechanism was adopted to simulate transient systemic and pulmonary blood pressure. Four intervals, i.e., the timing interval between mitral and aortic valve closure (TIMA), the timing interval between aortic and mitral valve closure (TIAM), the timing interval be- tween aortic and pulmonary valve closure (TIAP) and the timing interval between mitral and tricuspid valve closure (TIMT), are further defined in a heart cycle to illustrate their relationships to LVSBP. Simula- tions showed that the TIMA, TIAM and TIAP have strong negative correlations with LVSBP;meanwhile, the TIMT has a slightly negative relationship with LVSBP. To further validate the relationships, 6 healthy male subjects were experimentally evaluated. The intervals were extracted from non-invasively sampled heart sound signals taken from the surface of the thorax. The experiments showed relationships consistent with those obtained by simulations. These relationships may have potential applications for noninvasively accessing LVSBP in real-time with a high time resolution of one heartbeat.

Metformin capped Cu_(2)(OH)_(3)Cl nanosheets for chemodynamic wound disinfection

Recently,the development of chemodynamic therapy(CDT)offers a potential approach for fighting bacteria and treating infectious diseases,in which those CDT nanoagents can catalyze the generation of hydroxyl radicals(·OH)to destroy bacteria.In this work,to improve the efficiency of CDT,we have designed a new kind of metformin(Met)-capped two-dimensional Cu_(2)(OH)_(3)Cl nanosheets(CuOHCl-Met NSs)with good monodispersity,highly positive charge,and good biocompatibility for improving antibacterial effect and accelerating wound healing.With the capped Met,CuOHCl-Met NSs can effectively kill bacteria under a low concentration(6μg·mL^(−1))and a short treatment time(in 15 min),showing great advantages over the counterpart without Met.In vivo results demonstrated that CuOHCl-Met NSs accelerated the tissue regeneration of staphylococcus aureus-infected dermal wounds.This study provides a new pathway for improving efficiency of CDT nanoagent through using old drug.

Superhydrophobic Purple Orchid Leaves:Variation in Surface Morphology During the Vegetation Stages Leading to Diversity in Wettability

Learning hydrophobic phenomena from nature is always a promising approach to design the superhydrophobic surface.Purple orchid leaf which processes superhydrophobicity is an ideal plant model,and through mimicking its structure,the surface with excellent hydrophobicity is able to be obtained.However,the unclear of the diversity in wettability during the different vegetation stages and the absence of its relation to the surface morphology limits the further enhancement of the inspired structure.Here,we analyze the wettability difference as the leaf grows from tender to mature and then to senescent.Combining with the variation of surface morphology and chemical composition,the well-developed micro-scale basic unit bumps with dense nano-scale waxy layer on the surface are proven to be responsible for the best hydrophobicity of the mature leaf.The presence of the undeveloped or damaged micro-nano hierarchical structure reduces the formation of air pockets at the interface,leading to the decrease of the wettability for leaves at other stages.Moreover,by fabricating artificial leaves,the nano-waxy layer is proved to be more effective than that of the micro-bumps on the surface wettability.The results of study are of a great significance for guiding the design and fabrication of plant-inspired bionic superhydrophobic surface.

Characterization of OP9 as authentic mesenchymal stem cell line

Mesenchymal stem cells （MSCs） are multipotent stem cells capable of differentiating into various cell types,including osteocytes,chondrocytes,adipocytes,myocytes,and tenocytes.However,the difficulty or failure in expanding the mouse MSCs in vitro greatly hampered important research in animal models.The OP9,a stromal cell line from mouse bone marrow,has hematopoietic supportive capacity.Here,we report that the OP9 has the immunophenotype （CD45-,CD11b-,FLK-1-,CD31-,CD34-,CD44＋,CD29＋,Sca-1＋,CD86-,and MHCII-） identical to canonical mouse MSCs.The expression of CD140a＋,CD140b＋,α-SMA＋ and Calponin＋ suggested the perivascular origin of OP9.Functionally,the OP9 had strong clonogenic ability and could be induced into osteocytes,chondrocytes and adipocytes.The lymphocyte transformation test （LTT） and mixed leukocyte reaction （MLR） showed that the OP9 could suppress T lymphocyte proliferation stimulated by nonspecific mitogens （PHA） or allogeneic lymphocytes （BALB/c T cells）.Finally,the migration of OP9 could be efficiently induced by bFGF,IGF-1,IL-3,PDGF-BB,TGF-β1 and TGF-β3.In conclusion,the OP9 were bona fide MSCs,and such homogenous cell line will be helpful to delineate biological features of MSCs at the stem cell level.