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 quantitatively analyze the primary research characteristics and keywords of international and domestic papers in the field of capsule endoscopy with bibliometric methods, and to illustrate the progression of capsule endoscopy research and offer insights for researchers in this domain.Methods:The Stork and visualized software CiteSpace were used to search and analyze the literature on "capsule endoscopy" in the English database of PubMed and the Chinese database of CNKI from 2002 to 2022.Results:A total of 6 011 English articles were identified in the PubMed database during the specified period. Both the number of publications and their citation frequencies displayed an upward trend on a global and domestic scale. The growth rates of global and domestic English publications were 5% and 15%, respectively, with major contributions coming from the United States, Japan, China, Italy and Germany. Key areas of global research interest included magnetic capsule endoscopy, colon capsule endoscopy, inflammatory bowel disease, small bowel capsule endoscopy, capsule endoscopy images, and obscure gastrointestinal bleeding, etc. A total of 2 027 articles were retrieved in the CNKI database, with top three research institutions including Department of Gastroenterology, Changhai Hospital, Naval Medical University; Department of Gastroenterology, Nanfang Hospital, Southern Medical University; School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University. Emerging research keywords encompassed artificial intelligence, deep learning, and guidelines.Conclusion:The study reveals a gradual increase in global research activities related to capsule endoscopy, with China demonstrating significant international academic influence in this field.

Objective To provide a theoretical basis for radiation health supervision through an analysis of the situation of computed tomography (CT) equipment quality control and CT room radiological protection in Guangdong Province, China in recent years. Methods We collected the data of 392 times of CT quality control and radiological protection testing by a third-party radiological health technical service institution in Guangdong Province from 2019 to 2021. We analyzed the levels of CT-owning hospitals, CT manufacturers, CT quality control test results, and the pass rate of radiation protection tests. Results The examined CT scanners were from different levels of hospitals in Guangdong Province, and were manufactured by nine major CT equipment manufacturers at home and abroad. The pass rate of CT room radiological protection was 99.88%, and the ambient dose equivalent rates of five monitoring points exceeded the limit, with four at the control room door and one at the shield wall of the room. The overall pass rate of CT equipment quality control was 99.49%, and the non-conforming parameters were the accuracy of positioning light and the deviation of reconstructed slice thickness. Conclusion In recent years, CT equipment quality control and room radiation protection in Guangdong Province have been at a high level.

Objective:To report 2 young infants of sodium channel related epilepsy with SCN2A gene mutation, and to discuss the clinical characteristics of the disease and the efficacy and safety of lacosamide combined with the literature.Methods:Corresponding information of 2 children hospitalized in the Department of Neurology of Hunan Children′s Hospital in July 2021 and October 2021 was collected, including the symptoms, comprehensive physical examination, blood, cerebrospinal fluid, imaging, electrophysiological examination, diagnosis and treatment process, response to treatment and other clinical data, as well as the sequencing results of the whole exome of the children. The efficacy and safety of lacosamide were analyzed, and the related literatures of the Biomedical Literature Database, Wanfang Data Knowledge Service Platform and Chinese Knowledge Infrastructure Database were searched and reviewed.Results:Both of the 2 cases were girl. Their onset age was within 3 months. The initial symptoms were frequent convulsions and backward development. There was no structural abnormality in the head image. The convulsions could not be controlled according to conventional multidrug treatment. The seizures were quickly controlled with lacosamide. Now they have been followed up for 6 months. No obvious adverse reactions were found. Case 1 gene test results showed the SCN2A gene (chr2:166152333-166246334) heterozygous deletion, SCN1A gene (chr2:166847754-16693013) heterozygous deletion, the deletion size being about 5.72 Mb. Case 2 gene test results showed new missense mutation of SCN2A (c.1285G>A, p.Glu429Lys). There were dozens of seizures every day. They were treated with valproic acid, oxcarbazepine and levetiracetam successively. The seizures could not be controlled. Three focal seizures originated in the left temporal region were detected by electroencephalogram. There was no recurrence on the third day after adding lacosamide, and there was no attack after 5 months of follow-up. No obvious adverse reactions were found during follow-up.Conclusions:Sodium channel related epileptic encephalopathy often starts early, has frequent seizures, and can be accompanied by backward psychomotor development at the same time. The slow sodium channel blocker lacosamide has good efficacy and safety in the treatment of sodium channel-related epilepsy with SCN2A gene mutation or combined SCN1A gene mutation.

Objective To evaluate the efficacy of ultrasound-guided anterior quadratus lumborum block combined with general anesthesia for laparoscopic radical resection of rectal carcinoma. Methods A total of 80 patients of both sexes, of American Society of Anesthesiologists physical status Ⅰ or Ⅱ, aged 40-64 yr, scheduled for elective laparoscopic radical resection of rectal carcinoma, were divided into 2 groups ( n=40 each) using a random number table method: anterior quadratus lumborum block combined with general anesthesia group ( group QG) and general anesthesia group ( group G) . In group QG, anteri-or quadratus lumborum block was performed with 0. 33％ ropivacaine 25 ml and dexamethasone 5 mg under ultrasound guidance before operation, and the same procedure was performed on the other side. Combined intravenous-inhalational anesthesia was applied, propofol 3-5μg∕ml and remifentanil 3-5 ng∕ml were given by target-controlled infusion, and cisatracurium was intermittently injected in two groups. Patient-controlled intravenous analgesia with sufentanil 2μg∕kg was used for postoperative analgesia. The analgesic pump was set up to deliver a 2 ml bolus dose with a 15-min lockout interval. Bruggrmann comfort scale ( BCS) scores were recorded at 1, 6, 12, 24 and 48 h after operation ( T1-5 ) . Tramadol was used for rescue analgesic after operation. The consumption of remifentanil and sufentanil, requirement for tramadol, occurrence of adverse reactions and patients' satisfaction with postoperative analgesia were recorded. The emergence time, first ambulation time, time to first flatus∕poo and length of hospital stay were also recorded. The develop-ment of anterior quadratus lumborum block-related complications was recorded. Results Compared with group G, BCS scores were significantly increased at T4,5 , the consumption of remifentanil, requirement for tramadol and incidence of nausea and vomiting were decreased, patients' satisfaction with postoperative an-algesia was increased, and the emergence time, first ambulation time, time to first flatus∕poo and length of hospital stay were shortened in group QG (P<0. 05). Conclusion Ultrasound-guided anterior quadratus lumborum block combined with general anesthesia can reduce the consumption of opioids in the perioperative period and is helpful in improving outcomes when used for laparoscopic radical resection of rectal carcinoma.

Objective To evaluate the role of chemokine CXC-ligand 16 (CXCL16) in renal fibrosis following renal ischemia-reperfusion (I/R) injury in mice.Methods Twenty-four healthy male C57BL/6 mice,aged 8-10 weeks,weighing 20-30 g,were divided into 4 groups (n =6 each) using a random number table method:sham operation group (group S),sham operation plus anti-CXCL16 antibody group (group S+A),group I/R,and I/R plus anti-CXCL16 antibody group (group I/R+A).Renal ischemia was induced by occlusion of the left renal artery for 30 min followed by 72-h reperfusion,and the fight kidney was removed on 5th day in anesthetized mice.CXCL16 antibody 5 mg/kg and the equal volume of normal saline were intraperitoneally injected at 72 h after reperfusion twice a week for 2 consecutive weeks in I/R+A and I/R groups,respectively.Sham operation was performed,and the equal volume of CXCL16 antibody 5 mg/kg and normal saline were intraperitoneally injected at 72 h after reperfusion twice a week for 2 consecutive weeks in S+A and S groups,respectively.Orbital venous blood samples were collected at day 14 after reperfusion for determination of serum blood urea nitrogen (BUN) and creatinine (Cr) concentrations.Animals were then sacrificed and the left kidney was removed for measurement of the renal fibrosis size (using Sirius red staining),expression of t-smooth muscle actin (α-SMA),fibronectin (FN) and type Ⅰ collagen (Col-Ⅰ) in renal tissues by Western blot.Results Compared with group S,the serum BUN and Cr concentrations and renal fibrosis size were significantly increased,and the expression of α-SMA,FN and Col-Ⅰ was up-regulated in group I/R (P＜0.05).Compared with group I/R,the serum BUN and Cr concentrations and renal fibrosis size were significantly decreased,and the expression of α-SMA,FN and Col-Ⅰ was down-regulated in group I/R+A (P＜0.05).Conclusion CXCL16 is involved in the process of renal fibrosis following renal I/R injury in mice.

Objective To evaluate the effect of ultrasound-guided transverse abdominal plane block (TAPB) on postoperative analgesia in patients undergoing orthotopic liver transplantation under general anesthesia.Methods Forty American Society of Anesthesiologists physical status Ⅲ-V patients,with body mass index of 18-24 kg/m2,aged 18-64 yr,undergoing elective modified piggy-back orthotopic liver transplantation,were divided into 2 groups (n =20 each) by a random number table method:TAPB combined with general anesthesia group (TAPB-GA group) and general anesthesia group (GA group).In TAPB-GA group,two-point TAPB was performed below bilateral costal margins under ultrasound guidance after induction of general anesthesia,and a mixture of 0.33％ ropivacaine 15 ml plus 0.5％ dexamethasone 0.5 ml was injected into each point.The equal volume of normal saline was injected into each point instead in group GA.Patient-controlled intravenous analgesia was performed with sufentanil 2 μg/kg after operation in both groups.Sufentanil 5 μg was intravenously injected as rescue analgesic,and the visual analog scale score was mainrained ≤3 within 48 h after operation.The intraoperative consumption of remifentanil and extubation time after operation were recorded.The requirement for sufentanil as rescue analgesic and development of nausea and vomiting,itching and respiratory depression were recorded within 48 h after surgery.Results Compared with group GA,the intraoperative consumption of remifentanil and requirement for sufentanil as rescue analgesic within 48 h after surgery were significantly reduced,the time of extubation was shortened,and the incidence of nausea and vomiting,itching and respiratory depression was decreased in group TAPB-GA (P＜ 0.05).Conclusion Ultrasound-guided TAPB can provide better efficacy of postoperative analgesia with fewer adverse reactions in patients undergoing orthotopic liver transplantation under general anesthesia.

Objective To observe the protective effect of dexmedetomidine(Dex)at different doses com-bined with ulinastatin in lung resection patients with one lung ventilation. Methods 80 patients having undergone unilateral lung resection were divided into four groups randomly:control group(C group)and groups Dex 1-3,20 cases in each group.One lung ventilation(OLV)was used in all the groups during operation.The patients in groups Dex 1-3 were treated with 0.5,1.0,2.0 μg/kg combined with ulinastatin,and the C group with amount of normal sa-line instead.The comparisons were done among the four groups in terms of SOD,L-6,IL-10,serum malondialde-hyde(MDA)concentration at 5 min after endotracheal intubation(T0),30 min(T1),60 min(T2),120 min (T3)as well as the levels of FVC,FEVl and FEVl/FVC at 24 h,48 h and 72 h after surgery. Results In the groups C and Dex 1,SOD decreased at T1-4 and IL-6,MDA and IL-10 at T2-4 rose.SOD decreased at T2-4 in groups Dex 2-3 and MDA,IL-6 and IL-10 rose.Compared with group C,the levels of SOD and IL-10 at T2-4 in groups Dex 1-2 and at T1-4 in group Dex 3 rose. In groups Dex 1-3,postoperative FVC,FEVl and FEVl/FVC rose.Compared with group Dex 1 or 2 respectively,SOD and IL-10 at T2-4 in group Dex 3 significantly rose,but MDA and IL-6 significantly declined;FVC,FEVl and FEVl/FVC significantly rose 48 h and 72 h after surgery (P<0.05). Conclusion Dex combined with ulinastatin has a protective effect for patients with one lung ventila-tion after lung resection,with the best-suggested dose of 1.0 μg/kg.

Objective To evaluate the effect of resveratrol on the activity of NADPH oxidase during acute lung injury induced by intestinal ischemia-reperfusion (I/R) in rats.Methods Thirty-two pathogenfree healthy female Sprague-Dawley rats,weighing 180-230 g,were divided into 4 groups (n =8 each) using a random number table:sham operation group (Sham group),intestinal I/R group (I/R group),vehicle group (Veh group) and resveratrol group (Res group).Intestinal I/R was produced by occlusion of the superior mesenteric artery for 75 min followed by 4 h of reperfusion.In group Res,resveratrol 15 mg/kg was intraperitoneally injected for 5 consecutive days before establishment of the model and at 15 min before ischemia.The equal volume of vehicle (0.5％ alcohol) was intraperitoneally injected in group Veh.The equal volume of normal saline was intraperitoneally injected in Sham and I/R groups.At the end of reperfusion,the rats were sacrificed and the lung was removed for microscopic examination of pathologic changes which were scored and for determination of wet/dry weight ratio (W/D ratio),malondialdehyde (MDA) content and superoxide dismutase (SOD) activity (by colorimetric method) and expression of NADPH oxidase subunits (gp91phox and p47phox) in lung tissues (by Western blot).Results Compared with group Sham,pathologic scores,W/D ratio and MDA content were significantly increased,the expression of gp91phox and p47phox was up-regulated,and the activity of SOD was decreased in I/R and Veh groups (P＜0.05).Compared with I/R and Veh groups,pathologic scores,W/D ratio and MDA content were significantly decreased,the expression of gp91phox and p47phox was down-regulated,and the activity of SOD was increased in group Res (P＜0.05).Conclusion The mechanism by which resveratrol reduces intestinal I/R-induced acute lung injury is related to inhibiting NADPH oxidase-mediated oxidative stress response of rats.

Objective To observe the effect of acute normovolemic hemodilution(ANH)combined with enhanced recovery after surgery(ERAS)on immune function in patients undergoing hepatic lobectomy. Methods 80 patients were divided into two groups:ERAS group(group E),ANH combined with ERAS group(group AE). bleeding volume,blood transfusion,infused fluid volume,urine output during operation and clinical index after surgery were recorded. Exhaust and defecation time ,fluid intake time and hospitalization duration were also record-ed. Blood samples were obtained from the patients at 30 min before anesthesia induction(T1),immediately(T2), 24 h(T3),3 d(T4)and 7 d(T5)after the end of operation for determination of the expression of CD3+,CD4+, CD8+ on T cells and natural killer cell. Results In group E ,CD3+,CD4+ T-lymphocytes and NK cells at T2-3 decreased as compared with T0. Compared with group E ,no allogeneic blood transfusion cases were found and clinical index duration was shorter in group AE. CD3+,CD4+T-lymphocytes and NK cells at T2-3 increased in group AE as compared with those in Group E. The difference is significant (P < 0.05). Conclusion ANH combined with ERAS can decrease allogenic blood transfusion and increase post-operation immunologic function ,shorten the postoperative hospitalization time.