Escherichia coli BA002, in which the ldhA and pflB genes are deleted, cannot utilize glucose anaerobically due to the inability to regenerate NAD+. To restore glucose utilization, overexpression of nicotinic acid phosphoribosyltransferase (NAPRTase) encoded by the pncB gene, a rate-limiting enzyme of NAD(H) synthesis pathway, resulted in a significant increase in cell mass and succinate production under anaerobic conditions. However, a high concentration of pyruvate was accumulated. Thus, co-expression of NAPRTase and the heterologous pyruvate carboxylase (PYC) of Lactococcus lactis subsp. cremoris NZ9000 in recombinant E. coli BA016 was investigated. Results in 3 L fermentor showed that OD600 is 4.64 and BA016 consumed 35.00 g/L glucose and produced 25.09 g/L succinate after 112 h under anaerobic conditions. Overexpression of pncB and pyc in BA016, the accumulation of pyruvic acid was further decreased, and the formation of succinic acid was further increased.
Anaerobiosis ; Escherichia coli ; enzymology ; genetics ; metabolism ; Fermentation ; Genetic Engineering ; Glucose ; metabolism ; Industrial Microbiology ; Lactococcus lactis ; enzymology ; NAD ; metabolism ; Pentosyltransferases ; biosynthesis ; genetics ; Pyruvate Carboxylase ; biosynthesis ; genetics ; Succinic Acid ; metabolism

Objective To evaluate the relationship between the change of Heart-fatty acid-binding protein and myocardial injury/infarction in postoperative of off-pump coronary artery bypass grafting (OPCAB).Methods 59 patients (male 37 and female 22,from 46 to 83 years old) who were the first time to undergoing OPCAB were included in this study.Serial venous blood samples were taken at after induction of anesthesia,the OPCAB finished (after the last anastomosis),entered ICU,2,4 and 8 hours after the patient entered ICU,and at 1 and 2 day postoperative to test H-FABP.The cTnI and CK-MB were tested at 4 and 8 hours,after entering ICU,and at 1 and 2 days postoperative.Patients were divided into 3 groups by the changes of ECG and the level of cTnl at 8 hours after they entered ICU:normal group (group I,cTnI ＜0.1 ng/ml),myocardial injury group(group Ⅱ,cTnI 0.l-1.0 ng/ml) and.myocardial infarction group(group Ⅲ,cTnI ＞ 1.0 ng/ml).Results The level of H-FABP released was significantly higher in the myocardial infarction group than normal group and myocardial injury group (P ＜ 0.01).There is good correlation between the H-FABP and cTnI or CK-MB.But the peak level of H-FABP is earlier (finished OPCAB) (P ＜ 0.05),and it peaked early at 2h after entered ICU (P ＜ 0.01),it began to decrease at 4 hours after entered ICU and returned to baseline at 1 day postoperative,while the cTnI and CK-MB peaked at postoperative day 1 and 8h after entered ICU respectively,and maintained in higher level at postoperative 2 days.Conclusion There is good correlation between the H-FABP and perioperative myocardial infarction in OPCAB,and it has superiority compared with cTnI,which is as gold standard for perioperative myocardial infarction,on a certain degree.It can benefit from early detection of H-FABP for myocardial infarction in perioperative of OPCAB.

AIM AND METHODS: To explore the effects calcitonin gene-related peptide (CGRP) and endothelin-1(ET-1) on the mechanisms of hypoxic pulmonary hypertension (HPH),the contents of CGRP and ET-1 in plasma of pulmonary artery and thoracic aorta and in extractives of lung and ventricular tissues of the chronic hypoxic rats were determined by radioimmunoassay. The changes of their hemodynamic indices and right heart hypertrophy index were monitored simultaneously. RESULTS: The level of pulmonary artery plasma CGRP was significantly higher than that of thoracic aorta plasma,but just the reverse was ET-1 or the ratio of ET-1 and CGRP in control rats( P

Succinic acid production was inhibited by high osmotic pressure caused by the accumulation of sodium ions in the process of two-stage fermentation by Escherichia coli using Na2CO3 as the pH regulator. To enhance the resistance of this strain to osmotic stress, the possibility to isolate high NaCl-tolerant mutant strain of Escherichia coli for succinic acid production by metabolic evolution was investigated. The metabolic evolution system was used as a mutant-generating system, allowing the cells to be continuously cultured at the maximum specific growth rate. The mutant strain can grow at maximum rate in the condition of high osmotic by gradually improving the concentration of NaCl in a continuous culture. Then the high osmotic-tolerant mutant strain of E. coli XB4 was selected with NaCl as the osmo-regulator. When using Na2CO3 as the pH regulator, E. coli XB4 was used in a 7.0 L fermenter during two-stage fermentation. After 60 h anaerobic fermentation, the mutant strain XB4 produced 69.5 g/L succinic acid with a productivity of 1.18 g/(L x h), which were increased by 18.6% and 20% compared with that of the parent strain.
Drug Tolerance ; genetics ; Escherichia coli ; genetics ; isolation & purification ; metabolism ; Industrial Microbiology ; Metabolic Engineering ; methods ; Mutation ; Osmotic Pressure ; Sodium Chloride ; pharmacology ; Succinic Acid ; metabolism

Escherichia coli NZN111 is a promising strain with ldhA and pflB genes inactivated for the production of succinic acid. However, with these mutations, NAD+ could not be regenerated from NADH, and an unbalanced NADH/NAD+ ratio eliminated cell growth and glucose utilization under anaerobic conditions. Nicotinic acid mononucleotide adenylyltransferase (NAMNAT), encoded by the nadD gene, catalyzes the reaction from nicotinic acid mononucleotide (NaMN) to nicotinic acid adenine dinucleotide (NaAD) during the synthetic pathway of NAD(H). Overexpression of the nadD gene could enhance the concentration of NAD(H) and maintain a suitable NADH/NAD+ ratio. In this study, we constructed a recombinant strain E. coli NZN111/pTrc99a-nadD, and overexpressed NAMNAT with 1.0 mmol/L of IPTG under anaerobic conditions in sealed bottles. Compared to E. coli NZN111, the concentrations of NAD+ and NADH in the recombinant strain increased by 3.21-fold and 1.67-fold, respectively. The total concentration of NAD(H) was increased by 2.63-fold, and the ratio of NADH/NAD+ decreased from 0.64 to 0.42. The recombinant strain restored the cell growth and glucose utilization under anaerobic conditions. After 72 h, the recombinant strain could consume 14.0 g/L of glucose to produce 6.23 g/L of succinic acid, and the concentration of succinic acid was 19-fold higher than in E. coli NZN111.
Anaerobiosis ; Escherichia coli ; genetics ; metabolism ; Glucose ; metabolism ; Mutation ; NAD ; metabolism ; Nicotinamide-Nucleotide Adenylyltransferase ; genetics ; metabolism ; Recombinant Proteins ; genetics ; metabolism ; Succinic Acid ; metabolism

Objective:To explore the current situation of nursing human caring in hospital wards and analyze its influencing factors, so as to facilitate the development of nursing human caring practice.Methods:From July to November 2022, a total of 107 hospitals were surveyed through stratified convenience sampling method, and 4 072 ward nursing managers were recruited to finish the general information questionnaire and the ward nursing human caring status questionnaire. The general information included the region, class and type of the hospital, etc. The ward nursing human caring status questionnaire included 38 items in 5 dimensions of nursing human caring system and process, humanistic quality and training of nursing staff, humanistic environment and facilities, human caring procedures and measures, and human caring quality evaluation and improvement, with a full score of 190 points. Descriptive statistics were used to analyze the general data, independent samples t-test, ANOVA and correlation analysis were used to analyze the factors influencing the current status of nursing human caring in the ward, while multiple linear regression analysis was used to conduct a multivariate analysis. Results:The score of nursing human caring in hospital wards was 156.91±27.78. Whether the hospital had carried out nursing human caring pilot(demonstration) wards, whether the ward had previously been a hospital nursing human caring pilot(demonstration) nursing unit, the type of ward, and whether nursing managers had participated in human caring training were the influencing factors of the implication of nursing humanistic caring in wards( P<0.05). Conclusions:The practice of nursing human caring in hospital wards is at a good level, but needs to be further strengthened. Nursing managers should take systematically strategies to promote the development of nursing human caring practice.