β-hydroxy-β-methylbutyric acid (HMB) is widely applied in sports nutrition, disease prevention and other fields. However, chemical synthesis methods, limited by toxic reagents and violent reactions, can hardly meet the demands of green production. The biosynthesis method mainly utilizes enzymatic catalysis or metabolic engineering techniques for synthesis, and has the advantages of high efficiency, low cost, and sustainability. Therefore, the production of HMB by the biosynthesis method has a good application prospect. In this research, a biosynthesis-based production strategy for HMB was developed. By using L-leucine as the substrate and constructing a dual-enzyme co-expression system, we established an efficient catalytic process. At first, the enzymatic properties of L-amino acid deaminase (PvL-AAD) from Proteus vulgaris and 4-hydroxyphenylpyruvate dioxygenase (Rn4-HPPD) from Rattus norvegicus were characterized. Rn4-HPPD had low relative activity and required an acidic environment for catalysis. Based on the surface charge modification strategy of the enzyme protein, site-directed mutagenesis and combinatorial mutagenesis were conducted on 10 sites of Rn4-HPPD. A double mutant Rn4-HPPD^H18R/N302R was thus obtained, with the enzyme activities being 2.00 times and 2.39 times that of the wild type at pH 5.5 and pH 6.5, respectively. Subsequently, the expression of the two enzymes in Escherichia coli was optimized. After the optimal expression ratio of the two enzymes was determined as 1:3 and under the conditions of OD₆₀₀ of 70, pH 6.0, 35 ℃, Fe²⁺ concentration of 1.5 mmol/L, and feeding of the substrate in batches in a 5 L fermenter, the maximum yield of HMB reached 8.60 g/L. This study not only enhances the optimal pH and activity of Rn4-HPPD but also provides new approaches for the efficient microbial synthesis of HMB.
Escherichia coli/metabolism* ; Valerates/metabolism* ; Recombinant Proteins/biosynthesis* ; Animals ; Metabolic Engineering/methods* ; Rats ; Catalysis

【Objective】 To investigate the effect of optimized preoperative hemoglobin (Hb) level on clinical outcome in patients undergoing coronary artery bypass grafting (CABG). 【Methods】 Retrospective analysis was performed on patients who were selected to receive CABG from April 2020 to August 2021 in our hospital. Preoperative basic data, perioperative blood transfusion volume, blood transfusion rate, acute liver function impairment, renal function impairment (AKI), ICU stay, length of hospital stay, and in-hospital mortality of patients, meeting the inclusion criteria, were collected. According to the perioperative red blood cell transfusion, the optimal preoperative Hb threshold was calculated by receiver operating characteristic curve (ROC). According to the threshold, all patients were divided into two groups, and the blood transfusion volume and clinical outcomes of the two groups were compared to evaluate the predictive value of the optimal threshold of Hb. 【Results】 A total of 915 patients who met the inclusion criteria were enrolled in the study. The optimal threshold for predicting red blood cell transfusion rate by calculating preoperative Hb value by ROC curve was 118 g/L for males and 116g/L for females. Group A: Hb≤ threshold (n=293) was divided into the red blood cell transfusion group A1 and the red blood cell non-transfusion group A2. Group B: Hb>threshold (n=622) was divided into the red blood cell non-transfusion group B1 and no red blood cell non-transfusion group B2. The risk factors for perioperative red blood cell transfusion were age (OR=1.033 874, 95%CI 1.000 4-1.068 3, P<0.01), gender (female) (OR=3.268 5, 95%CI 2.353 1-4.540 0, P<0.01), BMI (OR=0.927 8, 95%CI 0.883 3-0.974 4, P<0.01), chronic renal insufficiency (CKD) (OR=2.041 1, 95%CI 1.347 8-3.091 0, P<0.01). Preoperative Hb≤ threshold (OR=3.517 4, 95%CI 2.502 1-4.944 7, P<0.01) was an independent risk factor for perioperative red blood cell transfusion. Perioperative red blood cell transfusion in patients with preoperative anemia further increases the incidence of postoperative complications (acute liver injury, AKI) and length of ICU stay. 【Conclusion】 Preoperative Hb≤ threshold can effectively predict perioperative red blood cell transfusion in patients with CABG, and increase the risk of postoperative acute liver injury, AKI, prolonged ICU stay and hospital stay. Optimizing the preoperative Hb level in CABG patients, increasing the Hb level to 118 g/L in males and 116 g/L in females can reduce the incidence of perioperative red blood cell transfusion and postoperative complications.

Objective:To analyze the correlation between the root resorption rate and tooth movement of the maxillary and mandibular incisors before and after orthodontic treatment in adult patients using cone-beam CT (CBCT), and to explore the related factors that affect the apical root resorption.Methods:In this retrospective study, 23 adult patients with classⅠor class Ⅱ division 1 malocclusion [2 males and 21 females, mean age (23.4±6.3) years, treatment time (2.1±0.7) years] who received orthodontic treatment with fixed appliance in Department of Oral & Cranio-Maxillofacial Surgery, Shanghai Ninth People′s Hospital from January 2017 to June 2021 were enrolled. Full-column CBCT examination was performed before and after treatment. A three-dimensional model was established to observe and record the volume of the maxillary and mandibular central and lateral incisors before and after treatment. The change of the incisal edge, the angle of rotation of the incisal edge, and the direction of the long axis of the tooth were also measured. The root resorption in each tooth before and after treatment was compared, and the root resorption rate was calculated. Pearson correlation analysis was performed on the root absorption rate before and after treatment with age, treatment time and tooth movement.Results:After treatment, the tooth volume of the maxillary and mandibular central and lateral incisors decreased significantly ( P<0.01). The root absorption volumes were (20.2±6.0) mm 3 and (11.2±4.7) mm 3 in maxillary central and lateral incisors, and (14.7±4.6) mm 3 and (14.8±5.0) mm 3 in mandibular central and lateral incisors, respectively. The root absorption rates were (9.49±1.75)% and (9.13±3.24)% in maxillary central and lateral incisors, and (8.56±3.43)% and (9.65±2.76)%, in mandibular central and lateral incisors, respectively ( F=0.56, P=0.640). The root resorption rate of maxillary central incisors had a weak positive correlation with the change of sagittal distance of incisal edge ( r=0.36, P=0.015). The root resorption rate of mandibular central incisors had a moderate positive correlation with the vertical movement distance ( r=0.48, P=0.001). The root resorption rate of mandibular lateral incisors was weakly positively correlated with the vertical movement of incisal edge and the treatment time ( r=0.35, P=0.016; r=0.34, P=0.021), and was moderately positively correlated wit the change of sagittal movement of incisal edge ( r=0.44, P=0.002). Conclusions:During orthodontic treatment, both maxillary and mandibular incisors had a certain degree of root resorption, which was related to sagittal and vertical movement of the incisors and the time of orthodontic treatment.

OBJECTIVETo investigate the effects of Sanren decoction on the immune function of rats with spleen-stomach damp-heat (DHSS) syndrome.

METHODSFifty male SD rats were randomly allocated into normal control group, DHSS model group, and 3 Sanren decoction groups (high, medium and low doses). The effects of the decoction on the body mass, rectal temperature (RT), water and food intake, histopathological changes of the gastrointestinal mucosa and serum levels of interleukin (IL)-4 and interferon (IFN)-γ were evaluated.

RESULTSThe serum levels of IFN-γ and IL-4 in the model group significantly increased compared with those in the control group (P<0.01), with a slightly increased IFN-γ/IL-4 ratio (P>0.05). Sanren decoction obviously reduced the rectal temperature and significantly decreased the production of both cytokines. High-dose Sanren decoction caused more markedly decreased IL-4 level (P<0.05) to result in a significantly increased IFN-γ/IL-4 ratio (P<0.05).

CONCLUSIONSA shift of Th1/Th2 balance toward Th1 immune response is demonstrated in rats with DHSS syndrome, and Sanren decoction produces a protective effect on the gastrointestinal mucosa by immunoregulation.

Animals ; Diagnosis, Differential ; Digestive System Diseases ; drug therapy ; immunology ; Inflammation ; drug therapy ; immunology ; Interferon-gamma ; blood ; Interleukin-4 ; blood ; Male ; Medicine, Chinese Traditional ; Rats ; Rats, Sprague-Dawley ; Syndrome ; Th1-Th2 Balance ; drug effects

Objective To evaluate the preventive efficacy of oral small-dose thyroid hormone tablet premedication for a short time on euthyroid sick syndrome (ESS) in children undergoing open heart surgery under cardiopulmonary bypass (CPB) .Methods Forty ASA Ⅰ or Ⅱ children aged 3-12 yr, weighing 10-30 kg, scheduled for elective congenital heart disease surgery under CPB, were randomly allocated into 2 groups ( n = 20 each):placebo group (group P) and thyroid hormone tablet group (group T). Group T received oral thyroid hormone tablets 0.4 mg/kg every day for 4 consecutive days before surgery, while group C were given placebo. CPB was routinely established, and mild hypothermia, moderate hemodilution and high flow perfusion were adopted. Blood samples were taken from radial veins before administration (baseline) and on 1st, 2nd and 4th day after surgery to detect the serum concentrations of triiodothyronine (T3), thyroxine (T4) and thyroid stimulating hormone (TSH).SP, DP and HR were recorded before administration, immediately after surgery, and on 1st and 2nd day after surgery. The endotracheal extubation time, length of ICU stay, application of positive inotropic agents and occurrence of ESS were recorded. Results No significant difference was found in hemodynamic parameters, endotracheal extubation time and length of ICU stay between the two groups ( P ＞ 0.05). As compared with the baseline values,the serum T3 levels on 1st, 2nd and 4th day after surgery, and the serum TSH levels on 1 st day after surgery were significantly decreased in the two groups, and the serum T4 levels were significantly decreased on 1 st day after surgery in group P ( P ＜ 0.05). The serum levels of T3 and T4 were significantly higher, the severity of postoperative ESS and the number of positive inotropic agent administration were significantly lower in group T than in group P (P ＜ 0.05 ). Conclusion Although oral small-dose thyroid hormone tablet premedication for 4 days (0.4 mg/kg per day) can reduce the severity of postoperative ESS, but it can not prevent the occurrence of ESS in children undergoing open heart surgery under CPB.