Novel biodegradable and pH-sensitive hydrogels composed of four types of pH-sensitive polyacrylic acid derivatives (PAAD) and a biodegradable poly(l-glutamic acid) (PGA) crosslinker were synthesized ...and characterized for oral delivery of proteins or peptides. The swelling ratios of hydrogels in buffer solutions showed a pH-dependent profile at different pH values. Insulin was loaded into the hydrogels as a model protein. The in vitro drug release experiment was carried out at different pH values and the release data suggested that both the pH and the type of the AAD unit played important roles in the drug release behaviors of the hydrogels. In vitro MTT assay indicated that the hydrogels displayed good cytocompatibility. After oral administration of insulin-loaded hydrogel particles to streptozotocin-induced diabetic rats at 60 IU/kg, the fasting plasma glucose level was reduced continuously to 67.4% within 7 h. These results indicated that the hydrogels are potential new vehicles for oral delivery of drugs.
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Biodegradable and pH‐responsive carboxymethyl cellulose/poly(acrylic acid) hybrid hydrogels are synthesized. The hydrogels deswell in acidic artificial gastric fluid (AGF) but rapidly swell in ...neutral artificial intestinal fluid (AIF), rendering selective enzymatic degradation of the gels as well as accelerated drug release from insulin‐loaded hydrogels in AIF. Oral administration of insulin‐loaded hydrogels to streptozotocin‐induced diabetic rats leads to a continuous decline in the fasting blood glucose level within 6 h post‐administration, and the relative pharmacological availability increases more than 10 times compared to oral administration of free insulin solution. The relative bioavailability of hydrogel‐encapsulated insulin after oral administration to healthy rabbits is 6.6%.
Biodegradable, pH‐responsive carboxymethyl cellulose/poly(acrylic acid) hydrogels are synthesized. Insulin is selectively released in neutral intestinal environment from insulin‐loaded hydrogels, rendering markedly enhanced oral bioavailability of insulin‐loaded gels compared to free insulin solution in animal tests.
Pinus Koraiensis
seeds have physiological dormancy. Cold stratification releases seed dormancy. The changes in metabolite profiles of dormant seeds and cold stratified seeds during shorter incubation ...time in a favorable condition for seed germination have been studied. However, a more-long-term detection of the changes in metabolites in dormant seeds can identify the real metabolic pathways responsible for dormancy. Metabolite composition was investigated in embryo and megagametophyte of primary physiological dormant seeds (DS) of
P. Koraiensis
collected at 0, 1, 2, 4, and 6 weeks of incubation and of non-primary physiological dormant seeds (NDS) sampled at 0 and 1 week of incubation, seed coat rupture stage, and radicle protrusion stage. Embryos contained higher levels of most metabolites than megagametophyte. Strong accumulation of most metabolites in DS occurred at 1 and 4 weeks of incubation. A larger reduction in the relative levels of most phosphorylated sugars and amino acids in NDS was found between 1-week-incubation and seed coat rupture stage. The relative levels of metabolites involved in carbohydrate metabolism, especially the pentose phosphate pathway (PPP) and tricarboxylic acid (TCA) cycle, were higher in the embryos of 4-week-incubated DS, but the relative contents of intermediate metabolites of most amino acid metabolism were lower compared to 1-week-incubated NDS. We suggested that the disturbed carbohydrate metabolism and amino acid metabolism in the embryos of DS after 4 weeks of incubation maybe related to primary dormancy. Our study provides information for a better understanding of the mechanism of seed dormancy.
Protein-based hydrogels usually do not exhibit high stretchability or toughness, significantly limiting the scope of their potential biomedical applications. Here we report the engineering of a ...chemically cross-linked, highly elastic and tough protein hydrogel using a mechanically extremely labile, de novo-designed protein that assumes the classical ferredoxin-like fold structure. Due to the low mechanical stability of the ferredoxin-like fold structure, swelling of hydrogels causes a significant fraction of the folded domains to unfold. Subsequent collapse and aggregation of unfolded ferredoxin-like domains leads to intertwining of physically and chemically cross-linked networks, entailing hydrogels with unusual physical and mechanical properties: a negative swelling ratio, high stretchability and toughness. These hydrogels can withstand an average strain of 450% before breaking and show massive energy dissipation. Upon relaxation, refolding of the ferredoxin-like domains enables the hydrogel to recover its massive hysteresis. This novel biomaterial may expand the scope of hydrogel applications in tissue engineering.
Alfalfa is a good green manure source, but its effect on rice growth has not been fully elucidated. Two green manure species, alfalfa and broad bean (Vicia faba L.), and two N fertilizer levels, ...alone or combination, were applied to a rice field. The results indicated that alfalfa had more pronounced effects on increasing soil labile phosphorus (P) fractions (including NaHCO
-Pi, NaOH-Pi), P uptake and soil enzyme activities (dehydrogenase, urease, acid phosphatase and β-glucosidase) than broad bean and N fertilizer. The transformation of NaHCO
-Po to labile P regulated by alfalfa played a significant direct and indirect effect on grain yield. Although a much lower N input from alfalfa addition, a similar grain yield with N fertilizer treatment was achieved, and the integration of alfalfa with N fertilizer produced the highest grain yield and P availability, which was associated with the highest urease, acid phosphatase and β-glucosidase activity in soil. These results indicate that alfalfa green manure had a great ability of increasing grain yield through enhancing P availability in rice paddy, which could give us a way to reduce N fertilizer application by enhancing P availability.
Camellia weiningensis Y. K. Li. sp. nov. (CW) is an endemic oil-tea species in Guizhou province, distributed in the alpine karst area, which exhibits cold resistance and better economic characters ...than C. oleifera (CO). The mechanism of cold response in CW seedlings has not been studied in depth. Herein, we performed anatomical, physiological, and metabolic analyses to assess the impact of cold stress on leaf structure, photosynthesis, and metabolites in CW and CO seedlings. Anatomical analysis of leaves showed CW seedlings had greater leaf and palisade thicknesses, tissue structure tightness, and palisade-spongy tissue ratio to enhance chilling stress (4 °C) tolerance, but freezing stress (−4 °C) caused loosening of the leaf tissue structure in both CW and CO seedlings. Photosynthetic analysis showed a reduction in the chlorophyll (Chl) fluorescence (Fv/Fm) and photosynthetic parameters under freezing stress in both CW and CO seedlings. Cold stress increased the abscisic acid (ABA) contents in both the Camellia species, and CW exhibited the highest ABA content under −4 °C treatment. Additionally, the indole-3-acetic acid (IAA) content was also increased in CW in response to cold stress. An obviously distinct metabolite composition was observed for CW and CO under different temperatures, and significantly changed metabolites (SCMs) were enriched under freezing stress. Prenol lipids, organooxygen compounds, and fatty acyls were the main metabolites in the two Camellia species in response to cold stress. The top key SCMs, such as medicoside G, cynarasaponin F, yuccoside C, and methionyl-proline were downregulated under freezing stress in both CW and CO. The contents of some key metabolites associated with sugar metabolism, such as UDP-glucose, UDP-D-apiose, and fructose 6-phosphate, were higher in CW than in CO, which may contribute to enhancing the cold resistance in CW. Our findings are helpful in explaining how CW adapt to alpine karst cold environments, and will provide a reference for cold tolerance improvement and application of stress-resistant breeding of Camellia in alpine and cold areas.
Background
Effective personal protective equipment (PPE) contribute to the prevention of COVID-19 infection. However, it is necessary to evaluate the potential risk of different medical protections ...in the isolation ward of COVID-19.
Objectives
We aimed to explore the dynamics in physiological indexes of medical staff under primary and secondary PPE in the isolation ward of COVID-19 and provide the scientific basis for determining the safe work strategy.
Materials and Methods
In this study, 30 female nurses were selected to simulate medical work under the primary or secondary PPE, respectively. The oral temperature, axillary temperature, heart rate, respiratory rate, blood oxygen saturation, and blood pressure were measured and recorded every 20 min. The subjective adverse symptoms were recorded every 30 min. The blood glucose and weight of the individuals were measured and recorded before and after the trial.
Results
The results indicated that the median trial persistence time in the participants with moderate-intensity work wearing the secondary PPE (70.0 min) was much lower than that with moderate-intensity work wearing the primary PPE (180 min) and with light-intensity work wearing the primary PPE (110 min;
p
< 0.05). Importantly, the heart rate, oral/axillary temperature, and respiratory rate of physiological indexes of the participants under moderate-intensity work wearing the secondary PPE increased significantly faster than the primary PPE (
p
< 0.001), while blood oxygen saturation decreased significantly faster than the primary PPE (
p
< 0.001). In addition, the proportions of subjective adverse symptoms (such as dry mouth, dizziness, palpitations, and anhelation) were much higher than primary PPE (
p
< 0.001). The average sweat volume and blood glucose consumption of participants under moderate-intensity work wearing primary PPE were higher than secondary PPE (
p
< 0.001).
Conclusion
The combination of an exacerbated workload and secondary PPE worn by COVID-19 healthcare workers increases the change in physiological indicators, and in some cases the adverse symptoms, which can affect and even suspend their medical work. For any medical institution, there is room for improvement in terms of bioethics of a “Job Well Done” to reduce the risks of medical activities under secondary PPE.
The Qinghai-Tibetan Plateau is a vast geographic area currently subject to climate warming. Improved knowledge of the CO
2
respiration dynamics of the Plateau alpine meadows and of the impact of ...grazing on CO
2
fluxes is highly desirable. Such information will assist land use planning. We measured soil and vegetation CO
2
efflux of alpine meadows using a closed chamber technique over diurnal cycles in winter, spring and summer. The annual, combined soil and plant respiration on ungrazed plots was 28.0 t CO
2
ha
−1
a
−1
, of which 3.7 t ha
−1
a
−1
occurred in winter, when plant respiration was undetectable. This suggests winter respiration was driven mainly by microbial oxidation of soil organic matter. The winter respiration observed in this study was sufficient to offset the growing season CO
2
sink reported for similar alpine meadows in other studies. Grazing increased herbage respiration in summer, presumably through stimulation of gross photosynthesis. From limited herbage production data, we estimate the sustainable yield of these meadows for grazing purposes to be about 500 kg herbage dry matter ha
−1
a
−1
. Addition of photosynthesis data and understanding of factors affecting soil carbon sequestration to more precisely determine the CO
2
balance of these grasslands is recommended.
Hydrothermal fluctuation is the major driving factor affecting greenhouse gas (GHG) emissions in wetlands, but how wetland drying regulates the temperature dependence of GHG emissions remains ...uncertain. An experimental incubation was carried out to study the interaction effects of temperature (5, 10, 15, 20°C) and moisture (40%, 60%, 100% WHC) on soil GHG emissions in a karst wetland. The results showed that: 1) the cumulative CO
2
and N
2
O emissions and global warming potential (GWP) increased with increasing temperature but decreased with soil drying. 2) There was a decreasing contribution of CO
2
and an increasing contribution of N
2
O to GWP with increasing temperature and moisture. 3) Soil CO
2
and N
2
O emissions and GWP were positively related to urease activity and negatively related to pH, soil organic matter and catalase. Soil CH
4
emissions were positively related to soil microbial biomass C and N. The hydrothermal changes, soil properties and their interaction explained 26.86%, 9.46% and 49.61% of the variation in GWP. Our results indicate that hydrothermal fluctuation has a significant effect on total GHG emissions by regulating soil properties.
Green manure application has been a good fertility management for crop growth and soil quality, but its effect on greenhouse gas intensity (
GHGI
) and net ecosystem carbon budget (
NECB
) of rice ...ecosystem is not well understood. Two green manure species, alfalfa (
Medicago sativa
L.) and broad beans (
Vicia faba
L.), and two N fertilization levels (0 and 200 kg ha
−1
), alone or in combination, were applied to rice paddy soils in 2012 and 2013. The results show that the grain yields increased by 25.36, 29.81, and 41.85 % for the N fertilizer, N + broad bean, and N + alfalfa treatments, respectively, compared with the no fertilizer. CH
4
and N
2
O emissions increased by 50.77 and 36.11 %, 30.70 and 75.04 % in N + broad bean and N + alfalfa treatments, respectively, compared to N fertilizer treatment. The average CH
4
and N
2
O emissions were 37.47 and 63.22 % higher in 2013 than in 2012, respectively, whereas the average soil temperature during the rice growth period was 2.1 °C higher in 2013 than in 2012. The highest value in
GHGI
was associated with the N + broad bean treatment (with a high C/N ratio), while the
NECB
and mass of soil total carbon change (
MSTC)
were highest in the N + alfalfa treatment (with a low C/N ratio). This result indicates that high C/N ratio green manures had high grain yields yet increased
GHGI
, while low C/N ratio green manures had even higher grains yields with increased
NECB
and
MSTC
.
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