Papers by Keyword: Metabolism

Abstract: Bioavailability of orally administered drugs can be influenced by many factors. Poor drug absorption across the intestinal membrane is one of the factors that contribute to low bioavailability of drugs. It has been suggested that the metabolism/active efflux in the small intestine is involved in the poor absorption of many drugs. Intestinal CYP3A4 and P-gp work coordinately to reduce the intracellular concentration of drugs. Recently, bioenhancers have been identified and extensively studied. The aim of this study was to evaluate natural furanocoumarins found in juices of common lime and kaffir lime as the potential enhancers for oral delivery by means of modulating CYP3A4 and/or P-gp activities. The role of isolated furanocoumarins on CYP3A4 was assessed by testosterone 6β-hydroxylation reaction, while the effect on P-gp was investigated using R123 and CAM uptake studies in Caco-2, as well as LLC-PK₁ and LLC-GA5-Col300. In the present study, we demonstrated that isopimpinellin isolated from common lime is the best CYP3A4 inhibitor among 4 isolated furanocoumarins, implying that isopimpinellin would possibly act as a bioenhancer by inhibiting pre-systemic metabolism. 6’,7’-Dihydroxybergamottin found in kaffir lime is a dual inhibitor of CYP3A4 and P-gp, suggest that it could potentially be used as a bioenhancer by inhibiting both pre-systemic metabolism and efflux mechanism. However, in vivo study should be further conducted to confirm these effects in the body.

Abstract: The draft genome of newly isolated Acidithiobacillus ferrivorans ZB-1 and DX-1 were deciphered to obtain a comprehensive insight into the genetic information and to discover the cellular mechanisms during its high activity in low temperature environment. Genome analysis speculated that Acidithiobacillus ferrivorans ZB-1 and DX-1 could fix carbon dioxide through the Calvin cycle and other central carbon metabolism potentially, and may be able to absorb and utilize nitrate or nitrite in the environment. The related cryophylactic genes (CspD, CspE, Fad and FabG) and gene clusters in fatty acid synthesis were discovered and suggested to play a crucial role in cold resistance.

Abstract: Anaerobic ammonium oxidation (anammox) process is a heated researched biotechnology for nitrogen removal in wastewater. The application of the process is limited due to its long start-up time and sensitivity to organic matters. This paper discussed the effects of acetate on anammox process. The nitrogen removal rate of anammox process was elevated at low acetate content (1 mmol/L) and decreased at high acetate content (3 and 4 mmol/L). The ratios among NH₄⁺-N, NO₂^--N and NO₃^--N were not related acetate content and remained at 1:1.50:0.07, but the ratios between acetate and three forms of nitrogen were acetate dependent.

Abstract: Bacillus sp. was stimulated by external low-voltage static electric field of different intensity at the same time. To make comparisons of the biomass, pH, the metabolism of Bacillus sp.and the surface morphologies of Bacillus sp.treated and untreated. The results showed that when the electric field strength was between 0.5V/cm and 3V/cm, the pH was bigger in test group than control group. The growth of Bacillus sp. was inhibited at 3V/cm, and promoted at 0.5V/cm to 2.5V/cm. The growth of Bacillus sp. was promoted maximumly at 0.5V/cm. Finally, we find that low-voltage static electric field didn’t damage the morphology. The appropriate electric field strength can enhance the metabolism of Bacillus sp.

Abstract: Much progress has been made toward understanding plant drought resistance. However, the coordinate responses of plant to drought on the basis of ABA level at physiological, ecological and molecular levels remains unclear. Here, the potted winter wheat (triticum aestivum) was cultivated under relative soil moisture (RSM ) respectively at 85% (well-watered), 65% (moderate stress), and 45% (severe stress), and a series of physiological and ecological parameters including ABA level, stomatal conductance, leaf temperature, leaf water potential, together with transcripts of ABA biosynthesis-metabolism key genes including 9-cis-epoxycarotenoid dioxygenase (TaNCED), ABA glucosyltransferase (TaGT), ABA 8'-hydroxylase (TaCYP707A), and β-glucosidase (TaBG) were carried out. We found that ABA contents responsive to soil water loss increased rapidly and showed a significantly-negative correlation with the stomatal conductance and the leaf water potential and a significantly-positive correlation with the leaf-air temperature difference, respectively. The continuous accumulation of ABA was resulted mainly from the increased transcripts of both TaNCEDs and TaBGs genes. The transcripts of TaCYP707A1 and TaGT declined sharply from 85% to 65% RSM and then increased slightly from 65% to 45% RSM, indicating that ABA metabolism not only accelerates the accumulation of ABA level but also contributes to maintain ABA homeostasis. In conclusion, the macroscopic-microscopic changes responsive to water deficient reflects the ABA-regulated, drought-resistance coordinate mechanisms at physiological, ecological and molecular levels in triticum aestivum.

Abstract: The stable isotope compositions of bivalve shells have been widely used to reconstruct palaeoclimate, but the metabolic effect obscured the climatic and environmental significance of the carbon isotope composition. In order to assess the contribution of metabolic C to the shell and ascertain whether its variations have any environmental or physiological significance, Corbicula fluminea (Müller, 1774) was bred in the laboratory last for one year; two shell samples (shell A and B) were selected at the end of the experiment to determine the carbon isotope composition of the shell increment that deposited during the experiment. The results indicated that ڄ¹³C_A ranged from 4.76 to 2.09 and ڄ¹³C_B from 8.49 to 2.89 . ڄ¹³C of shell A and B are both more negative than the predicted equilibrium value, indicated that the shells had used the metabolic carbon during the shell forming process. According to computation, the proportion of shell A was 32.0% to 52.0% (mean value 38.7%); and shell B was 42.7% to 92.1% (mean value 70.3%). Such exceptional high proportion of metabolic carbon to cultured C. fluminea shells quite different from the field C. fluminea shells and other previous studies results, and may suggest that the improper bred food that indicate by the slowly growth rate of species caused the bivalve abnormal biological behaviors, which induce complicated and exceptional metabolic effect. Therefore, it can be used as indicator of deviant food change events during bivalve growth.

Abstract: In anaerobic digestion system, the functional niche of hydrogen-producing acetogens (HPAs) is between acidogenic fermentation bacteria and methanogens. HPAs are quite difficult to be isolated by pure and ampliative cultures due to the obligate anaerobic metabolism property in syntrophic association with methanogenic. In order to enhance the HPAs activities in anaerobic disgestion, the physioecologic and metabolic properties of HPAs under different medium conditions, such as carbon and nitrogen type, influent temperature and pH was investigated in batch cultivation experiments. The result illustrated that under the cultivation temperature of 45°C and pH of 8.0, the butyrate, propionate and benzoate could be utilized by the syntrophic acetogenesis coculture, of which the uptake rate of butyrate was highest. The glucose and sucrose were repulsed however. The metabolic activity of HPAs could be enormously simulated as the mixture of tryptone and yeast was taken as the nitrogen source.

Abstract: Simulating dynamic behaviors of metabolic networks of a living cell plays an important role in system biology. As a part of dynamic model, the choice of objective function has a large influence on simulation accuracy for these behaviors. In this work, in order to precisely describe the biomass yield and substrate utilization in glycolytic metabolism of Escherichia coli, we try to modify the objective function of the existing dynamic model by using maximization of glucose utilization to replace the traditional objective one. After that, the dynamic model with the new objective is converted to a standard optimal control problem. And then we compute such model through the use of the penalty function methods. The results illustrate that the simulation curves perfectly agree with experiment data, especially with biomass concentration. Thereby, we conclude that completely utilizing substrate glucose is feasible to describe and improve the simulation accuracy on concentrations of some important metabolites in Escherichia coli. The completeness of investigating such models will be helpful and instructive for the application of bioengineering.

Abstract: Eco-city was researched from the basic characteristics and compared with existence form of life in this article. An eco-city shall form a living organism system as a complex organization of green building working as the main ecological circle in human society and civilization, demonstrating its nature of life as well. This paper analyzed the human as the most important part of a city, with both material and spiritual leading properties, elaborated that eco-city was similar to organism in the field of structure and composition, operation and control, development and evolution. It is concluded that human is the core energy and power of urban development in modern civilization.

Abstract: This paper extends our early study on discrete events system formulations of DNA hybridization, and focuses discussions on metabolism and gene mutation in Molecular Biology. Finite state machine (FSM) theory is extensively applied to represent key concepts and analyze the processes related to the biological phenomena mentioned above. The goal is to mathematically represent and interpret the process of metabolism and the effects to structures of protein macro molecule caused by gene mutation. We hope the proposed model will provide a foothold for introducing the information science and the control theory tools in Molecular Biology