Biomedical subjects

Guo-qing He

Publications and source records attributed to Guo-qing He.

12 recordsLinked to original sources

PubMed2006

Optimization of elastolysis conditions and elastolytic kinetic analysis with elastase from Bacillus licheniformis ZJUEL31410.

The solubilization of elastin by Bacillus licheniformis elastase cannot be analyzed by conventional kinetic methods because the biologically relevant substrate is insoluble and the concentration of enzyme-substrate complex has no physical meaning. In this paper we report the optimization of elastolysis conditions and analysis of elastolytic kinetics. Our results indicated that the hydrolyzing temperature and time are very important factors affecting elastolysis rate. The optimized conditions using central composite design were as follows: elastolysis temperature 50 degrees C, elastase concentration 1 x 10(4) U/ml, elastin 80 mg, elastolytic time 4 h. Investigation of the effects of substrate content, elastase concentration and pH was also revealed that low or high elastin content inhibits the elastolysis process. Increasing elastase improves elastin degradation, but high elastase may change the kinetics characterization. Alkaline environment can decrease elastin degradation rate and pH may affect elastolysis by changing elastase reaction pH. To further elucidate the elastolysis process, the logistic model was used to elastolysis kinetics study showing clearly that the logistic model can reasonably explain the elastolysis process, especially under lower elastase concentration. However, there is still need for more investigations with the aid of other methods, such as biochemical and molecular methods.

Bacillus↗

PubMed2006

Synthesis and paste properties of octenyl succinic anhydride modified early Indica rice starch.

Octenyl succinic anhydride (OSA) modified early Indica rice starch was prepared in aqueous slurry systems using response surface methodology. The paste properties of the OSA starch were also investigated. Results indicated that the suitable parameters for the preparation of OSA starch from early Indica rice starch were as follows: reaction period 4 h, reaction temperature 33.4 degrees C, pH of reaction system 8.4, concentration of starch slurry 36.8% (in proportion to water, w/w), amount of OSA 3% (in proportion to starch, w/w). The degree of substitution was 0.0188 and the reaction efficiency was 81.0%. The results of paste properties showed that with increased OSA modification, the starch derivatives had higher paste clarity, decreased retrogradation and better freeze-thaw stability.

Biochemistry↗

PubMed2006

[Extraction optimization study of flavonoids from Humulus lupulus].

OBJECTIVE: To optimize extracting parameters of flavonoids from Humulus lupulus. METHOD: Based on the single factors test on ethanol concentration, material and solvent ratio, extracting temperature and extracting time, orthogonal test was performed and the best combination was confirmed. RESULT: With the optimized technology, the maximal extracting amount of flavonoids from H. lupulus was 78 mg x g(-1). CONCLUSION: The optimal techniques obtained are 45% ethanol extracting at 60 degrees C with material and solvent ratio 1:25 for 90 min.

Ethanol↗

PubMed2005

Optimization of angiotensin I-converting enzyme (ACE) inhibition by rice dregs hydrolysates using response surface methodology.

Angiotensin I-converting enzyme (ACE) inhibitory peptides have been shown to have antihypertensive effects and have been utilized for physiologically functional foods and pharmaceuticals. The ACE inhibitory ability of a hydrolysate is determined by its peptide composition. However, the peptide composition of a hydrolysate depends on proteolytic enzyme and the hydrolysis conditions. In this study, the effect of process conditions on the ACE inhibitory activity of rice dregs hydrolyzed with a trypsin was investigated systematically using response surface methodology. It was shown that the ACE inhibitory activity of rice dregs hydrolysates could be controlled by regulation of five process conditions. Hydrolysis conditions for optimal ACE inhibition were defined using the response surface model of fractional factorial design (FFD), steepest ascent design, and central composite design (CCD).

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2005

Application of derivative ratio spectrophotometry for determination of beta-carotene and astaxanthin from Phaffia rhodozyma extract.

A derivative ratio spectrophotometric method was used for the simultaneous determination of beta-carotene and astaxanthin produced from Phaffia rhodozyma. Absorbencies of a series of the standard carotenoids in the range of 441 nm to 490 nm demonstrated that their absorptive spectra accorded with Beer's law and that the additivity when the concentrations of beta-carotene and astaxanthin and their mixture were within the range of 0 to 5 microg/ml, 0 to 6 microg/ml, and 0 to 6 microg/ml, respectively. When the wavelength interval (lambda) at 2 nm was selected to calculate the first derivative ratio spectra values, the first derivative amplitudes at 461 nm and 466 nm were suitable for quantitatively determining beta-carotene and astaxanthin, respectively. Effect of divisor on derivative ratio spectra could be neglected; any concentration used as divisor in range of 1.0 to 4.0 microg/ml is ideal for calculating the derivative ratio spectra values of the two carotenoids. Calibration graphs were established for beta-carotene within 0-6.0 microg/ml and for astaxanthin within 0-5.0 microg/ml with their corresponding regressive equations in: y=-0.0082x-0.0002 and y=0.0146x-0.0006, respectively. R-square values in excess of 0.999 indicated the good linearity of the calibration graphs. Sample recovery rates were found satisfactory (>99%) with relative standard deviations (RSD) of less than 5%. This method was successfully applied to simultaneous determination of beta-carotene and astaxanthin in the laboratory-prepared mixtures and the extract from the Phaffia rhodozyma culture.

Algorithms↗

PubMed2005

Partitioning and purification of extracellular beta-1,3-1,4-glucanase in aqueous two-phase systems.

The partition behaviors of beta-1,3-1,4-glucanase, alpha-amylase and neutral proteases from clarified and whole fermentation broths of Bacillus subtilis ZJF-1A5 were investigated. An aqueous two-phase system (polyethylene glycol (PEG)/MgSO(4)) was examined with regard to the effects of PEG molecular weight (MW) and concentration, MgSO(4) concentration, pH and NaCl concentration on enzyme partition and extraction. The MW and concentration of PEG were found to have significant effects on enzyme partition and extraction with low MW PEG showing the greatest benefit in the partition and extraction of beta-glucanase with the PEG/MgSO(4) system. MgSO(4) concentration influenced the partition and extraction of beta-glucanase significantly. pH had little effect on beta-glucanase or proteases partition but affected alpha-amylase partition when pH was over 7.0. The addition of NaCl had little effect on the partition behavior of beta-glucanase but had very significant effects on the partitioning of alpha-amylase and on the neutral proteases. The partition behaviors of beta-glucanase, alpha-amylase and proteases in whole broth were also investigated and results were similar to those obtained with clarified fermentation broth. A two-step process for purifying beta-glucanase was developed, which achieved beta-glucanase recovery of 65.3% and specific activity of 14027 U/mg, 6.6 times improvement over the whole broth.

Bacillus subtilis↗

PubMed2005

Batch and fed-batch production of butyric acid by clostridium butyricum ZJUCB.

The production of butyric acid by Clostridium butyricum ZJUCB at various pH values was investigated. In order to study the effect of pH on cell growth, butyric acid biosynthesis and reducing sugar consumption, different cultivation pH values ranging from 6.0 to 7.5 were evaluated in 5-L bioreactor. In controlled pH batch fermentation, the optimum pH for cell growth and butyric acid production was 6.5 with a cell yield of 3.65 g/L and butyric acid yield of 12.25 g/L. Based on these results, this study then compared batch and fed-batch fermentation of butyric acid production at pH 6.5. Maximum value (16.74 g/L) of butyric acid concentration was obtained in fed-batch fermentation compared to 12.25 g/L in batch fermentation. It was concluded that cultivation under fed-batch fermentation mode could enhance butyric acid production significantly (P<0.01) by C. butyricum ZJUCB.

Bioreactors↗

PubMed2005

Effective extraction of elastase from Bacillus sp. fermentation broth using aqueous two-phase system.

This paper presents the evaluation of an aqueous two-phase system (ATPS) for extracting elastase produced by Bacillus sp. EL31410. The elastase and cell partition behavior in polyethylene glycol (PEG)/salt systems was investigated. The suitable system for elastase extraction was PEG/KH(2)PO(4)-K(2)HPO(4), in which elastase is mainly partitioned into the PEG-rich phase, while the cells remained in the other phase. The influence of defined system parameters (e.g. PEG molecular mass, pH, NaCl addition) on the partitioning behavior of elastase is described. The concentration of phase forming components, PEG and KH(2)PO(4)-K(2)HPO(4), was optimized for elastase recovery by means of response surface methodology, and it was found that they greatly influenced extraction recovery. The optimal ATPS was 23.1% (w/w) PEG 2 000 and 11.7% (w/w) KH(2)PO(4)-K(2)HPO(4). The predicted recovery was about 89.5%, so this process is suggested to be a rapid and convenient method for elastase extraction.

Bacillus↗

PubMed2004

Improved elastase production by Bacillus sp. EL31410--further optimization and kinetics studies of culture medium for batch fermentation.

An efficient culture medium producing a bacterial elastase with high yields was developed further following preliminary studies by means of response surface method. Central composite design (CCD) and response surface methodology were applied to optimize the medium constituents. A central composite design was used to explain the combined effect of three medium constituents, viz, glucose, K(2)HPO(4), MgSO(4).7H(2)O. The strain produced more elastase in the completely optimized medium, as compared with the partially optimized medium. The fitted model of the second model, as per RSM, showed that glucose was 7.4 g/100 ml, casein 1.13 g/100 ml, corn steep flour 0.616 g/100 ml, K(2)HPO(4) 0.206 g/100 ml and MgSO(4).7H(2)O 0.034 g/100 ml. The fermentation kinetics of these two culture media in the flask experiments were analyzed. It was found that the highest elastase productivity occurred at 54 hours. Higher glucose concentration had inhibitory effect on elastase production. At the same time, we observed that the glucose consumption rate was slow in the completely optimized medium, which can explain the lag period of the highest elastase production. Some metal ions and surfactant additives also affected elastase production and cell growth.

Bacillus↗

PubMed2003

[Management of critical severe acute respiratory syndrome and risk factors for death].

OBJECTIVE: To investigate the management of critical severe acute respiratory syndrome (SARS) and possible risk factors for death. METHODS: Thirty-three patients with SARS referred to Guangzhou Institute of Respiratory Disease (GIRD) between December 2002 and March 2003 were studied retrospectively. Paired t-test using statistical software SPSS 10.0 was employed to compare the respiratory frequency and pulse O(2) saturation (SpO(2)) before and after noninvasive ventilation with continuous positive airway pressure (CPAP) on the 33 patients. Among them, 18 patients who presented with SpO(2) of 90% - 93% at rest under O(2) inhalation 5 L/min were further recorded for their SpO(2) during slight physical movement and CPAP. The possible death-related risk factors including age, underlying diseases, leucocytosis, thrombocytopenia, and lymphopenia were analyzed by the Mantel-Haenszel chi(2) test. RESULTS: The respiratory frequencies were significantly decreased and SpO(2) was improved in the 33 patients after one hour of noninvasive ventilation. The SpO(2) in the latter 18 patients fell during slight physical movement and improved one hour after CPAP (p < 0.01). The RRs of the five death predictors concerning thrombocytopenia, age (> 50 yrs, underlying diseases, leucocytosis, and lymphopenia were 25.83, 8.57, 6.40, 1.64, and 1.17, respectively, with the 95% CI of 3.64 - 183.59, 1.94 - 37.83, 1.75 - 23.33, 0.38 - 7.05 and 0.16 - 8.48, respectively. Management with corticosteroids effectively ameliorated and suppressed the development of pulmonary fibrosis. CONCLUSIONS: Noninvasive ventilation relieves dyspnea and SpO(2) in patients with critical SARS, and should also be employed in those with SpO(2) of 90% - 93% at rest under O(2) inhalation 5 L/min. Noninvasive as an add-on management may probably cut down on the dosage and duration of corticosteriod therapy. Among 5 possible risk factors, 3 were recognized as death-related, turning out to be thrombocytopenia, age (> 50 yrs) and underlying diseases.

Adrenal Cortex Hormones↗

PubMed2003

[Severe acute respiratory syndrome in 78 patients: a retrospective study].

OBJECTIVE: To analyze the clinical features of severe acute respiratory syndrome (SARS) and the diagnosis and treatment of the disease. METHODS: Seventy-eight patients with SARS referred to the Guangzhou Institute of Respiratory Diseases (GIRD), China from December 22, 2002 to March 2003 were studied retrospectively. The data reviewed included those of clinical manifestations, laboratory investigation and roentgenology. RESULTS: The patients consisted of 42 men and 36 women, aged 20 - 75 years (mean 37.5 +/- 11.6 years), including 44 infected health-care professionals. Clinical symptoms of these patients were fever (100%), coughing (88%), and dyspnea (80%). Routine blood test revealed WBCs <4.0 x 10(9)/L in 12 patients (15%), (4.0 -10.0) x 10(9)/L in 49 (63%), and over 10.0 x 10(9)/L in 17 (22%) [average (7.6 +/- 5.0) x 10(9)/L]. The level of neutrophilic granulocyte was 0.75 +/- 0.13 and that of lymphocyte was 0.18 +/- 0.11. Chest X-ray and CT scanning revealed changes related to pneumonia. The transmission of the disease was likely via close contact with contagious droplets. The prevalences of acute lung injury (ALI,37 patients) and acute respiratory distress syndrome (ARDS, 21 of the 37 patients) were considerably high among the patients. Seven patients who developed ARDS complicated with MODS died. CONCLUSIONS: A history of close contact, fever, X-ray signs of pneumonia and normal or lowered WBC counts are favorable for the diagnosis of SARS. Recognition of ALI as the important index for critical SARS and comprehensive supportive management are of paramount importance in decreasing the mortality of patients with SARS.

Adult↗

PubMedDate not supplied

Optimization of cultural conditions for thermostable beta-1,3-1,4-glucanase production by Bacillus subtilis ZJF-1A5.

The optimization of cultural conditions for Beta-glucanase production by Bacillus subtilis ZJF-1A5 was investigated in flask trials. Temperature had great effect on Beta-glucanase production which maximized at optimal temperature of 37 degrees C and decreased significantly when temperature was over 37 degrees C. Charge quantity affected Beta-glucanase production significantly. Adding oxygen vector N-dodecane or acetic ether benefited Beta-glucanase production, but it depended on the concentration and charge quantity. The results of fractional factorial design showed that age and size of inoculum and shaking speed were the key factors affecting Beta-glucanase production and the cultivation time span to reach the highest Beta-glucanase activity. The optimal cultural conditions for Beta-glucanase production obtained with CCD were as follows: inoculum age and size (16 h, 3.82%(v/v)), shaking speed 210 r/min, charge quantity of 30 mL in 250 mL flask and initial pH 7.0, cultured at 37 degrees C for 50 h. Repeated experimental results accorded with those predicted by a second-order polynomial model. The amount of Beta-glucanase, Alpha-amylase and neutral protease produced by B subtilis ZJF-1A5 was associated partially with cell growth. Those three enzymes' activities increased following the cell growth and increased significantly when cells entered the stationary phase.

Bacillus subtilis↗