Influence of selection of domain shape on parameters of microdosimetric kinetic model / 中华放射医学与防护杂志

Objective:To calculate the single-event dose-averaged specific energy of particles delivered in spherical domains based on the track structure model and using triple integration, and to investigate the influence of the domain shape on the key model parameters of microdosimetric kinetic model (MKM) and its corresponding physical significance.Methods:The domains are assumed to be cylinders and spheres, respectively. With α 0, domain radius, rd, and nucleus radius, Rn, as undetermined coefficients, the nuclear charge numbers, kinetic energies and their corresponding LETs of three kinds of charged particles ( 3He, 12C, 20Ne) as independent variables, D10 as dependent variable, the mean value of squared residuals, J2, between the D10 calculated values and D10 experimental values as the optimization objective, the final fitting values of the above undetermined coefficients of human salivary gland (HSG) cells and Chinese hamster lung (V79) cells obtained after iteration by the robust least square method are the optimal model parameter values of MKM. Results:For HSG cells, cylindrical domain: α 0=0.073/Gy, rd=0.29 μm, Rn=4.1 μm, J2=0.039 7 Gy 2; spherical domain: α 0=0.023/Gy, rd=0.29 μm, Rn=4.4 μm, J2=0.039 3 Gy 2; For V79 cells, cylindrical domain: α 0=0.114/Gy, rd=0.25 μm, Rn=3.8 μm, J2=0.097 4 Gy 2; spherical domain: α 0=0.095/Gy, rd=0.26 μm, Rn=4.1 μm, J2=0.096 9 Gy 2. Conclusions:For the same type of cells, cylindrical and spherical domains were selected respectively, and there are significant differences in MKM parameters obtained by fitting. The fitting values of the domain radius, rd of the two shapes of domains show no significant difference, while the fitting values of α0 of spherical domains are smaller than those of cylindrical domains, the fitting values of nucleus radius, Rn, of spherical domain are larger than those of cylindrical domains, closer to the nucleus radius observed by fluorescence microscopy. In the low LET (<20 keV/μm) region, D10 calculated according to the parameters of the two different shapes of domains are different, so the selection of the domain shape will cause differences in the relative biological effectiveness(RBE) calculation of proton in the region near Bragg peak.

Production, characterization and kinetic model of biosurfactant produced by lactic acid bacteria

BACKGROUND Biosurfactants are surface active molecules produced by microorganisms which have the ability to disrupt the plasma membrane. Biosurfactant properties are important in the food, pharmaceu tical and oil industries. Lactic acid bacteria can produce cell-bound and excreted biosurfactants. RESULTS The biosurfactant-producing ability of three Lactobacillus strains was analyzed, and the effects of carbon and nitrogen sources and aeration conditions were studied. The three species of lactobacillus eval uated were able to produce biosurfactants in anaerobic conditions, which was measured as the capacity of one extract to reduce the surface tension compared to a control. The decreasing order of biosurfactant production was L. plantarum>Lactobacillus sp.>L. acidophilus. Lactose was a better carbon source than glu cose, achieving a 23.8% reduction in surface tension versus 12.9% for glucose. Two complex nitrogen sources are required for growth and biosurfactant production. The maximum production was reached at 48 h under stationary conditions. However, the highest level of production occurred in the exponential phase. Biosurfactant exhibits a critical micelle concentration of 0.359 ± 0.001 g/L and a low toxicity against E. coli. Fourier transform infrared spectroscopy indicated a glycoprotein structure. Additionally, the kinetics of fermentation were modeled using a logistic model for the biomass and the product, achieving a good fit (R2 > 0.9). CONCLUSIONS L. plantarum derived biosurfactant production was enhanced using adequate carbon and nitrogen sources, the biosurfactant is complex in structure and because of its low toxicity could be applied to enhance cell permeability in E. coli

Potential application of a knowledgebase of iron metabolism of Acidithiobacillus ferrooxidans as an alternative platform

BACKGROUND: Acidithiobacillus ferrooxidans is a facultative anaerobe that depends on ferrous ion oxidation as well as reduced sulfur oxidation to obtain energy and is widely applied in metallurgy, environmental protection, and soil remediation. With the accumulation of experimental data, metabolic mechanisms, kinetic models, and several databases have been established. However, scattered data are not conducive to understanding A. ferrooxidans that necessitates updated information informed by systems biology. RESULTS: Here, we constructed a knowledgebase of iron metabolism of A. ferrooxidans (KIMAf) system by integrating public databases and reviewing the literature, including the database of bioleaching substrates (DBS), the database of bioleaching metallic ion-related proteins (MIRP), the A. ferrooxidans bioinformation database (Af-info), and the database for dynamics model of bioleaching (DDMB). The DBS and MIRP incorporate common bioleaching substrates and metal ion-related proteins. Af-info and DDMB integrate nucleotide, gene, protein, and kinetic model information. Statistical analysis was performed to elucidate the distribution of isolated A. ferrooxidans strains, evolutionary and metabolic advances, and the development of bioleaching models. CONCLUSIONS: This comprehensive system provides researchers with a platform of available iron metabolism-related resources of A. ferrooxidans and facilitates its application.

Study on extraction kinetics of Salviae Miltiorrhizae Radix et Rhizoma: model establishment and investigation of critical process parameters / 中国中药杂志

In this study, Fick's first law and partition equilibrium were used to represent the internal and external mass transfer processes of Salviae Miltiorrhizae Radix et Rhizoma at the macroscopic level, and a mass transfer model was established. The specific surface area was integrated into the mass transfer resistance, which effectively avoided the irregular shape of medicinal materials and expanded the application scope of the model. Meanwhile, the mass transfer model was further combined with the kinetic model of salvia-nolic acid degradation to establish the extraction kinetic models of salvianolic acid B, lithospermic acid and Danshensu. The model was applied to study the extraction process of Salviae Miltiorrhizae Radix et Rhizoma. According to the sensitivity analysis results, the relative error of the model prediction was within 5% near the maximum extraction rate(320 min), and the prediction performance of the model was good. According to the investigation results of different process parameters, stirring could significantly accelerate the mass transfer rate of salvianolic acid B, while the mass transfer resistance and degradation rate constant were not affected by solvent-to-solid ratio. The linear relationship between the reciprocal of temperature and the logarithm of mass transfer resistance was good(R~2=0.996), indicating that the temperature and mass transfer resistance conformed to Arrhenius formula. In addition, we also found that the concentration changes of lithospermic acid and Danshensu were weakly affected by mass transferwhen the extraction temperature was higher than 358 K. This study has provided the basis for the process optimization and quality control of traditional Chinese medicine extraction.

Application of affinity chromatography and its mathematical model in study of active components of traditional Chinese medicine / 中国中药杂志

Affinity chromatography is characterized by its high specificity,high recovery rate and sensitivity,and it has been widely used in the selection of active ingredients of traditional Chinese medicine,separation and enrichment of low molecular weight sugars and protein peptides,research on mechanism of action and discovery of targets.This paper reviewed the application of affinity chromatography and its adsorption isotherm model,kinetic model and adsorption thermodynamic mechanism in the field of traditional Chinese medicine.This summarizes and provides thinking for comprehensive applications of affinity chromatography theory in the field of active ingredient screening,purification and medicine interaction.

Study on Extraction Kinetic Comparison of Chlorogenic Acid in Lonicerae Japonicae Flos and Lonicerae Flos / 中国中医药信息杂志

Objective To explore the extraction kinetic deviation of the chlorogenic acid (ChA) in Lonicerae Japonicae Flos and Lonicerae Flos through established extract kinetic model of closed system of Chinese materia medica. Methods The content of ChA (W0) and ρ2in Lonicerae Japonicae Flos and Lonicerae Flos were determined by HPLC; The V1and V2were measured by water absorbing further to calculate V0; The value of M, N, L, α, β, and π were estimated by curve fitting using SPSS19.0 edition; The extraction kinetic parameters k, k1′, k2′, ρ1, tmax, cmax, AUC, P%, and D% were calculated by Excel; their similarity was calculate by the total quantum statistical moment similarity (TQSMS). Results The V0, V1,and V2for Lonicerae Japonicae Flos were 18.69, 9.50, and 30.20 mL, respectively. The W0for the ChA in Lonicerae Japonicae Flos were 3.75%, and ρ2was 0.884; The V0, V1, and V2for Lonicerae Flos were 12.79, 7.80, and 37.00 mL, respectively. The W0for the ChA in Lonicerae Flos were 5.67%, and ρ2was 1.020; The extraction kinetic profiles for ChA in Lonicerae Japonicae Flos and Lonicerae Flos were fitted three compartment model. The main kinetic parameters as k were 0.1101, 0.3755 h-1; k1′ were 3.632, 3.288 h-1; k2′ were 53.12, 55.28 h-1; ρ1were 2.731, 2.751; tmaxwere 0.299 5, 0.216 3 h; cmaxwere 0.134 0, 0.252 7 mg/mL; AUC were 3.405, 1.560 h; P% were 35.73% and 44.57%; D% were 0.916 2% and 2.680 7%, respectively. Their TQSMS was 0.963 8, which indicated that the extraction kinetics of ChA in Lonicerae Japonicae Flos and Lonicerae Flos had good similarity. Conclusion The extraction kinetic model described the dissolution behavior and deviation of extraction kinetic profiles for ChA in Lonicerae Japonicae Flos and Lonicerae Flos objectively and effectively. This research can provide some references for further study on extraction processes and preparation of Lonicerae Japonicae Flos and Lonicerae Flos.

Growth kinetic models of five species of Lactobacilli and lactose consumption in batch submerged culture

Abstract Kinetic behaviors of five Lactobacillus strains were investigated with Contois and Exponential models. Awareness of kinetic behavior of microorganisms is essential for their industrial process design and scale up. The consistency of experimental data was evaluated using Excel software. L. bulgaricus was introduced as the most efficient strain with the highest biomass and lactic acid yield of 0.119 and 0.602 g g-1 consumed lactose, respectively. The biomass and carbohydrate yield of L. fermentum and L. lactis were slightly less and close to L. bulgaricus. Biomass and lactic acid production yield of 0.117 and 0.358 for L. fermentum and 0.114 and 0.437 g g-1 for L.actobacillus lactis were obtained. L. casei and L. delbrueckii had the less biomass yield, nearly 11.8 and 22.7% less than L. bulgaricus, respectively. L. bulgaricus (R 2 = 0.9500 and 0.9156) and L. casei (R 2 = 0.9552 and 0.8401) showed acceptable consistency with both models. The investigation revealed that the above mentioned models are not suitable to describe the kinetic behavior of L. fermentum (R 2 = 0.9367 and 0.6991), L. delbrueckii (R 2 = 0.9493 and 0.7724) and L. lactis (R 2 = 0.8730 and 0.6451). Contois rate equation is a suitable model to describe the kinetic of Lactobacilli. Specific cell growth rate for L. bulgaricus, L. casei, L. fermentum, L. delbrueckii and L. lactis with Contois model in order 3.2, 3.9, 67.6, 10.4 and 9.8-fold of Exponential model.

Scaling-up batch conditions for efficient sucrose hydrolysis catalyzed by an immobilized recombinant Pichia pastoris cells in a stirrer tank reactor

Background: Invert sugar is used greatly in food and pharmaceutical industries. This paper describes scaling-up batch conditions for sucrose inversion catalyzed by the recombinant Pichia pastoris BfrA4X whole cells expressing Thermotoga maritima invertase entrapped in calcium alginate beads. For the first time, we describe the application of a kinetic model to predict the fractional conversion expected during sucrose hydrolysis reaction in both, a model and a prototype bioreactor with 0.5- and 5-L working volume, respectively. Results: Different scaled-up criteria used to operate the 0.5-L bioreactor were analyzed to explore the invert sugar large scale production. After model inversion studies, a 5-L scaled-up reaction system was performed in a 7-L stirred reactor. Both scaled-up criteria, immobilized biocatalyst dosage and stirring speed, were analyzed in each type of bioreactors and the collected data were used to ensure an efficient scale-up of this biocatalyst. Conclusions: To date, there is not enough information to describe the large-scale production of invert sugar using different scaled-up criteria such as dose of immobilized biocatalyst and stirring speed effect on mass transfer. The present study results constitute a valuable tool to successfully carry out this type of high-scale operation for industrial purposes.

Simulação numérica e ensaios experimentais da remoção de Fe (III) da água para utilização nas indústrias alimentícias / Numerical simulation and experimental tests of removal of Fe (III) from water for use in food industry

RESUMO Neste estudo foram realizadas as cinéticas e isotermas de adsorção dos íons Fe (III) presentes em afluentes sintéticos utilizando como adsorvente carvão ativado de casca de coco. O objetivo foi a obtenção dos parâmetros cinéticos e de equilíbrio do processo para assim simular diferentes condições operacionais em uma coluna de adsorção em leito fixo. Foram avaliadas a influência de três diferentes temperaturas na adsorção de Fe (III), sendo que o aumento da temperatura indicou adsorção exotérmica. A isoterma de Freundlich representou melhor os dados experimentais. Também foi realizado o estudo cinético e o modelo que apresentou melhor os dados experimentais foi o modelo de Pseudo-Primeira Ordem para as três concentrações estudadas. O método de Volumes Finitos foi utilizado na discretização das equações matemáticas e um algoritmo computacional foi implementado em linguagem FORTRAN. O código computacional foi validado com dados experimentais encontrados na literatura (erro máximo de 6,2%) podendo-se assim simular diferentes condições operacionais do sistema de adsorção com aplicação na indústria alimentícia.

ABSTRACT In this study were performed the kinetics and isotherms of adsorption of the ions Fe (III) from synthetic affluent using activated carbon from coconut shell as adsorbent. The objective was to obtain the equilibrium and kinetic parameters of the process and thereby simulating different operating conditions in a adsorption column fixed bed. It was evaluated the influence of three temperatures different on the adsorption of Fe (III), in which the temperature increase indicated adsorption exotherm. The Freundlich isotherm showed the best fit to the experimental data. At the kinetic study the model that best fit to the experimental data was the model Pseudo-First Order for the three concentrations studied. The finite volume method was used for discretization of the mathematical equations and a computational algorithm was implemented in FORTRAN. The computational code was validated with experimental data found in the literature (maximum error of 6.2%) can thus simulate different operating conditions of the system.

Concentration Prediction of Total Flavonoids in Aurantii Fructus Extraction Process: Locally Weighted Regression versus Kinetic Model Equation Based on Fick's Law / 中草药·英文版

Objective: To predict the total flavonoids concentration of Aurantii Fructus fried with bran in its extraction process. Methods: Ultraviolet spectrophotometry was used to determine the concentration of total flavonoids in different extraction time (t) and solvent load (M). Then the predicted procedure was carried out using the following data: 1) based on Ficks second law, the parameters of the kinetic model could be deduced and the equation was established; 2) Locally weighted regression (LWR) code was developed in the WEKA software environment to predict the concentration. And then we used both methods to predict the concentration of total flavonoids in new experiments. Results: After comparing the predicted results with the experimental data, the LWR model had better accuracy and performance in the prediction. Conclusions: LWR is applied to analyze the extraction process of Chinese herb for the first time, and it is totally fit for the extraction. LWR-based system is a more simple and accurate way to predict than the established equation. It is a good choice especially for a process which exists no clear rules, and can be used in the real-time control during the process.

Fluid volume kinetics of dilutional hyponatremia; a shock syndrome revisited

OBJECTIVE: To evaluate whether the pathophysiology of shock syndromes can be better understood by comparing central hemodynamics with kinetic data on fluid and electrolyte shifts. METHODS: We studied the dilutional hyponatremic shock that developed in response to overhydration with electrolyte-free irrigating fluid - the so-called ‘transurethral resection syndrome' - by comparing cardiac output, arterial pressures, and volume kinetic parameters in 17 pigs that were administered 150 ml/kg of either 1.5% glycine or 5% mannitol by intravenous infusion over 90 minutes. RESULTS: Natriuresis appeared to be the key factor promoting hypovolemic hypotension 15-20 minutes after fluid administration ended. Excessive sodium excretion, due to osmotic diuresis caused by the irrigant solutes, was associated with high estimates of the elimination rate constant (k10) and low or negative estimates of the rate constant describing re-distribution of fluid to the plasma after translocation to the interstitium (k21). These characteristics indicated a high urinary flow rate and the development of peripheral edema at the expense of plasma volume and were correlated with reductions in cardiac output. The same general effects of natriuresis were observed for both irrigating solutions, although the volume of infused 1.5% glycine had a higher tendency to enter the intracellular fluid space. CONCLUSION: Comparisons between hemodynamics and fluid turnover showed a likely sequence of events that led to hypovolemia despite intravenous administration of large amounts of fluid. .

Application of mathematical models in research of Chinese materia medica / 中草药

Based on the research results of the extraction, pharmacokinetics, and pharmacodynamics of Chinese materia medica (CMM), this paper thoroughly summarizes the principles and approaches of the corresponding mathematical models, and briefly makes a comparsion analysis on their strength and weakness. Referring to the associating data, the representatives were selected. Mathematical models with pros and cons can conduct the quantitatively analysis of study of CMM, and achieve the goals of precision, calculability, predicatability, and controllability. Mathematical models can effectively transform the qualitative problems in the study of CMM to the quantitative ones, unveil the objective laws between the quantities and promote the scientific development of CMM.

Optimization of moisture obsorption dynamic model fitting for Chinese materia medica extract powder under different humidity conditions / 中草药

Objective: To optimize the kinetic model that could accurately describe the moisture absorption progress of Chinese materia medica (CMM) extract powder, to quantify the adsorption process scientifically and to provide the theoretical basis for the further study on controlling the hygroscopicity of CMM extract powder by changing the physical properties. Methods: We chosed five models fitting the hygroscopic rate curve of fifty-one kinds of typical CMM extract powder under the low-, mid-, and high-humidity conditions, as evaluation indexes in R2, RSS, and AIC values, to make the initial screening of optimum kinetic model fitting. Results: Both the double exponential model and the Weibull distribution model could reflect the moisture absorption kinetics of CMM extract powder, but the double exponential model had a better adaptability than the Weibull distribution model under different humidity conditions. Conclusion: The double exponential model is suitable for reflecting the moisture absorption kinetics of CMM extract powder.

Study on Flavonoids Producing and Kinetics in Cell Suspension Culture of Eucommia ulmoides Oliv / 中国生物工程杂志

The type of basic media and the contents of plant growth substances were investigated by orthogonal design experiment,and also the effects of different culture conditions on the growth of suspension cells and the accumulation of total flavonoids in Eucommia ulmoides were studied.The results showed that B5 medium supplemented with 0.5mg/L NAA,0.6mg/L 6-BA and 30g/L sucrose,at initial pH 5.0～5.5,20g(FW)/L inoculation quantity and 110 r/min of rotation speed was a preferable culture conditions for E.ulmoides suspension cells growth and flavonoids synthesis.The results of metabolic kinetics analysis for E.ulmoides cell suspension culture showed that the logistic and Luedeking-Piret equations can be used for describing the kinetics of cell growth,sucrose consumption and flavonoids production during the process.The maximum specific growth rate(?m),the actual growth yield based on sucrose(YG) and maintenance coefficient(m) were 0.417/d,0.619g/g and 0.0206g/(g?d-1) respectively.All these outcomes could give a basis for establishing the suspension cell culture of E.ulmoides and production of the natural active components in large-scale.

Assessment of total body water of patients on hemodialysis with urea kinetic model / 北京大学学报(医学版)

Objective:To propose a method to evaluate the total body water (TBW) of patients on hemodialysis with urea kinetic model (UKM), and compare it with body surface bio-impedance spectrum (BIS) analysis. Methods:We enrolled 24 adult patients with end stage renal disease (ESRD) without hyper-catabolism in our dialysis center. All of them had been on hemodialysis for more than 3 months. TBW was measured with BIS analysis immediately before and after dialysis session, and one hour after hemodialysis session. Spent dialysate was collected; blood samples were taken before and one hour after hemodialysis session, TBW before hemodialysis session were calculated by UKM. Results:Patients were 6 men and 18 women, the average age was (51.2?13.5) years and the average time on dialysis was (33.2?36.7) months. Causes of ESRD included chronic glomerulonephritis (8 patients), diabetic nephropathy (1 patients), hypertensive renal damage (1 patients), interstitial nephritis(two patients), chronic pyelonephritis (two patients). The average ultrafiltration volume was (2.7?1.0) L (0.5-4.4 L) . Plasma urea concentrations were (23.06?5.76) mmol/L and (8.15?2.06) mmol/L before and one hour after hemodialysis session, respectively. There was no significant difference between TBW measured immediately after and one hour after hemodialysis session with BIS analysis [(29.9?8.8) L and (29.8?8.6) L, respectively; average difference was (0.1?0.9)L, P=0.70]. These two measurements correlated very well (Pearson r=0.99, P

Integration of pharmacokinetics and pharmacodynamics in antibiotic drug development and pharmacotherapy / 中国临床药理学与治疗学

Integration of pharmacokinetics(PK)/pharmacodynamics(PD)in antibiotic drug development allows the dosage regimen to be optimized,so that the desired effect can be achieved in a large proportion of the target patient population.In vitro kinetic and in vivo animal models have been extensively used in the evaluation of antibiotics.The value of these pre-clinical models in the PK and PD characterization of antibiotics is critically reviewed.A model based clinical development of antibiotics with integrating MIC distribution,PK parameter distribution,the PD target from animal models of infection,and the protein binding of the test drug,is also reviewed.