The adult spinal cord of mammals contains a certain amount of neural precursor cells, but these endogenous cells have a limited capacity for replacement of lost cells after spinal cord injury. The ...exogenous stem cells transplantation has become a therapeutic strategy for spinal cord repairing because of their immunomodulatory and differentiation capacity. In addition, dental stem cells originating from the cranial neural crest might be candidate cell sources for neural engineering.
Human dental follicle stem cells (DFSCs), stem cells from apical papilla (SCAPs) and dental pulp stem cells (DPSCs) were isolated and identified in vitro, then green GFP-labeled stem cells with pellets were transplanted into completely transected spinal cord. The functional recovery of rats and multiple neuro-regenerative mechanisms were explored.
The dental stem cells, especially DFSCs, demonstrated the potential in repairing the completely transected spinal cord and promote functional recovery after injury. The major involved mechanisms were speculated below: First, dental stem cells inhibited the expression of interleukin-1β to reduce the inflammatory response; second, they inhibited the expression of ras homolog gene family member A (RhoA) to promote neurite regeneration; third, they inhibited the sulfonylurea receptor1 (SUR-1) expression to reduce progressive hemorrhagic necrosis; lastly, parts of the transplanted cells survived and differentiated into mature neurons and oligodendrocytes but not astrocyte, which is beneficial for promoting axons growth.
Dental stem cells presented remarkable tissue regenerative capability after spinal cord injury through immunomodulatory, differentiation and protection capacity.
We cryopreserved mouse tooth germs with widely open cervical margins of the enamel organ to overcome difficulties in cryoprotectant permeation and tested their efficacy by transplanting them into ...recipient mice. The upper right first molar germs of 8-day-old donor mice were extracted and categorized into the following four groups according to cryopreservation time: no cryopreservation, 1 week, 1 month, and 3 months. The donor tooth germs were transplanted into the upper right first molar germ sockets of the 8-day-old recipient mice. The upper left first molars of the recipient mice were used as controls. The outcome of the transplantation was assessed at 1, 2, and 3 weeks after transplantation. Stereomicroscopic evaluation revealed that most of the transplanted teeth erupted by 3 weeks after transplantation. Micro-computed tomography analysis revealed root elongation in the transplanted groups as well as in the controls. There was no significant difference between the cryopreserved and non-cryopreserved transplanted teeth, but the roots of the cryopreserved teeth were significantly shorter than those of the control teeth. Histological examination revealed root and periodontal ligament formations in all the transplanted groups. These results suggest that the transplantation of cryopreserved tooth germs facilitates subsequent root elongation and tooth eruption.
Racemic vinylallenes are shown to be effective substrates for catalytic multicomponent diastereo‐ and enantioselective 1,6‐conjugate addition of multifunctional allyl moieties to easily accessible ...α,β,γ,δ‐unsaturated diesters. Reactions may be catalyzed by 5.0 mol % of a readily accessible NHC‐Cu complex at ambient temperature, and other than a vinylallene, involve B2(pin)2 and an α,β,γ,δ‐unsaturated diester. A variety of vinylallenes were converted to products bearing a Z‐trisubstituted alkenyl‐B(pin) moiety, a vinyl group, a β,γ‐unsaturated diester unit, and vicinal stereogenic centers in up to 67 % yield, 87:13 Z/E ratio, >98:2 d.r., and 98:2 e.r. Chemoselective modifications involving the alkenyl‐B(pin), the vinyl, or the 1,2‐disubstituted olefin moieties were carried out to demonstrate versatility and utility. Stereochemical models, based on mechanistic and DFT studies, demonstrate the dynamic behavior of intermediated Cu‐allyl species and account for various selectivity profiles.
No longer ignored: Readily accessible racemic vinylallenes are shown to be attractive substrates for catalytic multicomponent diastereo‐, and enantioselective 1,6‐conjugate additions. In just one step, highly complex structures containing a Z‐trisubstituted alkenyl‐B(pin) moiety, a vinyl group, a β,γ‐unsaturated diester unit, and vicinal stereogenic centers are generated in up to 67 % yield, 87:13 Z/E selectivity, >98:2 d.r., and 98:2 e.r.
The outstanding performance of aluminized explosives is attributed to the substantial energy released through aluminum (Al) reactions during post-detonation flow. However, the influences of Al powder ...size on the explosion power of aluminized explosives sometimes vary significantly across different time scales, which may suggest potential differences in Al reaction processes. To investigate the size-dependent reaction behavior of Al powders at different time scales, a novel experimental apparatus was employed to measure the velocity of a rod propelled by the detonation products of RDX/Al explosives (with Al powder sizes of 1.9 µm or 47.1 µm)1 at ∼1 ms, and the results were compared to those obtained from previous tube tests at around 30 µs. The experimental findings reveal that the impact of Al powder size on the metal-driven capability of aluminized explosives is not substantial at either 1 ms or 30 µs. Given the inadequacy of the phenomenological equation of state for studying the Al reaction due to its inability to ensure the uniqueness of the reaction process, we investigated the tburn∝dAln law using the Gurney energy method, where dAl and tburn denote the powder size and combustion time of Al powders, respectively. The values of n (0.031 and 0.038) were examined for the first time in post-detonation flow, which are significantly smaller than those observed in quasi-static flow. These results substantiate that the weak powder size effect on Al reaction is likely a prevalent phenomenon for micron-sized Al powders in post-detonation flow, attributable to the high pressure and high velocity characteristic of such flows.
New biocontrol strategies are urgently needed to combat vector-borne infectious diseases. This study presents a low-cost method to produce a potential mosquito insecticide that utilizes the ...microalgae released into suburban water sources to control mosquito populations. Chlorella microalgae are ubiquitous in local waters, which were chosen as the host for genetic transfection. This species facilitated the recombinant algae to adapt to the prevailing environmental conditions with rapid growth and high relative abundance. The procedure involved microalgae RNAi-based insecticides developed using short hairpin RNAs targeting the Aedes aegypti chitin synthase A (chsa) gene in Chlorella. These insecticides effectively silenced the chsa gene, inhibiting Aedes metamorphosis in the laboratory and simulated-field trials. This study explored the impact of recombinant microalgae on the phytoplankton and zooplankton in suburban waters. High-throughput sequencing revealed that rapid reproduction of recombinant Chlorella indirectly caused the disappearance of some phytoplankton and reduced the protozoan species. This study demonstrated that a recombinant microalgae-based insecticide could effectively reduce the population of Aedes mosquitoes in the laboratory and simulated field trials. However, the impact of this technology on the environment and ecology requires further investigation.
Although aluminized explosives are used worldwide, the post-detonation reaction of aluminum (Al) particles has not been sufficiently elucidated. Herein, a self-consistent calculation strategy, which ...performs iterative thermochemical calculations based on the first law of thermodynamics, has been proposed to study the post-detonation reaction of Al particles. By implementing a rod test driven by the detonation products of 3,5-trinitrohexahydro-s-triazine/Al (RDX/Al), the two-stage reaction of Al particles was researched by using a new thermochemical code that involved an Al particle temperature model and a chemical kinetic model. The key factors that determine the Al temperature were analyzed through the flow theory. The calculated results indicated that the Al particle temperature significantly influenced the Al particle reaction, which has rarely been studied before. Consequently, three conclusions were obtained: First, the overall reaction intensity of the Al particles increased significantly with an increase in the Al temperature. Second, in the detonation products, the ratio of the internal energy to the working energy increased with the Al temperature. Finally, a unique formula representing the incomplete oxidation of Al particles was derived. The reliability of this research was confirmed by performing three comparisons: First, the calculated temperature of the RDX/Al detonation products was observed to be in good agreement with the measured value qualitatively and quantitatively. Second, the calculated interval of the maximum internal energy increment in the RDX/Al detonation products overlapped with the calorimetric values. Third, the calculated Al reaction energy was in accordance with that observed using other thermochemical codes and the empirical method.
•An integrated indicator system for the special assessment of oases (the Oasis Integrated Model) is established.•The Oases Integrated Model was used in the Tarim River Basin (TRB) during ...1990–2020.•The salinity and meteorological indicators play an imperative role in the spatial distribution of artificial and natural oases.•Na ion could better explain the distribution of artificial oases, and Mg ion could better illustrate the distribution of natural oases.
Understanding the distribution of natural and artificial oases is essential for effective management of desert oases and water resources in arid regions. In order to explore characterization of Oases, we developed an ensemble method for the identification of factors influencing the distribution of oases in the upper reaches of the Tarim River Basin (TRB), China. To determine the affected elements of artificial and natural oases in arid lands through multi-function choices from 1990 to 2020, the Oases Integrated Analysis Model (OIAM) was used. The following input data was included in the OIAM: meteorological conditions, salinity, depth of groundwater, time sequence of Landsat images, and environmental chemicals such as calcium, bicarbonate, potassium, sodium, sulfate, and fluoride ions. Several functional methods were used to assess the efficiency of the OIAM. The results indicated that the OIAM consistently outperformed stable Wi (spatial contribution rate to Oases’ indicators). Moreover, the results from OIAM indicated that salinity and meteorological indicators influenced the spatial distribution of artificial and natural oases. For environmental chemical, Na and Mg ions were strongly associated with the distribution of artificial and natural oases, respectively. This indicates that the OIAM model effectively identifies factors influencing the distribution of artificial and natural oases in arid regions, and thus can be applied to other similar regions.
Among all the adult stem cells, odontogenic stem cells inherit the characterization of neurogenic potential of their precursor ones–the cranial crest cells. Dental follicle cells (DFCs), one of the ...special kind of odontogenic stem cells, are raising interest in applying to regenerative medicine for they possess multi-differentiation potential, relatively free access and ethic-friendly characteristic. Parkinson’s disease (PD), as one of the common neurodegenerative disorders, affects about 0.3% of the general population. Stem cell therapies are thought to be effective to treat it. Aiming at tackling ethical-concernings, confined sources and practically applicational limits, we made use of dopaminergic neurongenic differentiation potential of the DFCs and dedicated every effort to applying them as promising cell source for treating PD. Dental follicle cells were cultured from human dental follicle tissues collected from 12 to 18-year-old teenagers’ completely impacted third molars. Our data demonstrated that hDFCs were expressing mesenchymal stem cell-associated surface markers, and possessed the ability of osteogenic, adipogenic and neurogenic differentiation in vitro. Additionally, hDFCs formed neuron-like cells in vitro and in vivo, as well as expressing dopaminergic-neuronogenic marker–TH. Moreover, hDFCs survived in the transplanted areas of the Parkinson’s disease model of mouse over six weeks post-surgery, and the number of TH-positive DFCs in the DFCs-Grafted group surpassed its counterpart of the MPTP group with statistically significant difference. This study indicated that hDFCs might be a promising source of dopaminergic neurons for functional transplantation, and encouraged further detailed studies on the potential of hDFCs for treating PD.
A Co(0)-catalyzed intramolecular alkyne/benzocyclobutenone coupling through C–C cleavage of benzocyclobutenones is described. Co2(CO)8/P3,5-(CF3)2C6H33 was discovered to be an effective metal/ligand ...combination, which exhibits complementary catalytic activity to the previously established rhodium catalyst. In particular, the C8-substituted substrates failed in the Rh system, but succeeded with the Co catalysis. Experimental and computational studies show that the initially formed tetrahedral dicobalt-alkyne complex undergoes C1–C2 activation via oxidative addition with Co(0), followed by migratory insertion and reductive elimination to give the β-naphthol products.
More than half of the world's population suffers from epidemic diseases that are spread by mosquitoes. The primary strategy used to stop the spread of mosquito-borne diseases is vector control. ...Interference RNA (RNAi) is a powerful tool for controlling insect populations and may be less susceptible to insect resistance than other strategies. However, public concerns have been raised because of the transfer of antibiotic resistance marker genes to environmental microorganisms after integration into the recipient genome, thus allowing the pathogen to acquire resistance. Therefore, in the present study, we modified the 3-hydroxykynurenine transaminase (3hkt) and hormone receptor 3 (hr3) RNAi vectors to remove antibiotic resistance marker genes and retain the expression cassette of the inverse repeat sequence of the 3hkt/hr3 target gene. This recombinant microalgal marker-free RNAi insecticide was subsequently added to the suburban water in a simulated-field trial to test its ability to control mosquito population.
The expression cassette of the 3hkt/hr3 inverted repeat sequence and a DNA fragment of the argininosuccinate lyase gene without the ampicillin resistance gene were obtained using restriction enzyme digestion and recovery. After the cotransformation of Chlamydomonas, the recombinant algae was then employed to feed Aedes albopictus larvae. Ten and 300 larvae were used in small- and large-scale laboratory Ae.albopictus feeding trials, respectively. Simulated field trials were conducted using Meishe River water that was complemented with recombinant Chlamydomonas. Moreover, the impact of recombinant microalgae on phytoplankton and zooplankton in the released water was explored via high-throughput sequencing.
The marker-free RNAi-recombinant Chlamydomonas effectively silenced the 3hkt/hr3 target gene, resulting in the inhibition of Ae. albopictus development and also in the high rate of Ae. albopictus larvae mortality in the laboratory and simulated field trials. In addition, the results confirmed that the effect of recombinant Chlamydomonas on plankton in the released water was similar to that of the nontransgenic Chlamydomonas, which could reduce the abundance and species of plankton.
The marker-free RNAi-recombinant Chlamydomonas are highly lethal to the Ae. albopictus mosquito, and their effect on plankton in released water is similar to that of the nontransgenic algal strains, which reduces the abundance and species of plankton. Thus, marker-free recombinant Chlamydomonas can be used for mosquito biorational control and mosquito-borne disease prevention.
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