Collagen is a major structural protein in the matrix of animal cells and the most widely distributed and abundant functional protein in mammals. Collagen’s good biocompatibility, biodegradability and biological activity make it a very valuable biomaterial. According to the source of collagen, it can be broadly categorized into two types: one is animal collagen; the other is recombinant collagen. Animal collagen is mainly extracted and purified from animal connective tissues by chemical methods, such as acid, alkali and enzyme methods, etc. Recombinant collagen refers to collagen produced by gene splicing technology, where the amino acid sequence is first designed and improved according to one’s own needs, and the gene sequence of improved recombinant collagen is highly consistent with that of human beings, and then the designed gene sequence is cloned into the appropriate vector, and then transferred to the appropriate expression vector. The designed gene sequence is cloned into a suitable vector, and then transferred to a suitable expression system for full expression, and finally the target protein is obtained by extraction and purification technology. Recombinant collagen has excellent histocompatibility and water solubility, can be directly absorbed by the human body and participate in the construction of collagen, remodeling of the extracellular matrix, cell growth, wound healing and site filling, etc., which has demonstrated significant effects, and has become the focus of the development of modern biomedical materials. This paper firstly elaborates the structure, type, and tissue distribution of human collagen, as well as the associated genetic diseases of different types of collagen, then introduces the specific process of producing animal source collagen and recombinant collagen, explains the advantages of recombinant collagen production method, and then introduces the various systems of expressing recombinant collagen, as well as their advantages and disadvantages, and finally briefly introduces the application of animal collagen, focusing on the use of animal collagen in the development of biopharmaceutical materials. In terms of application, it focuses on the use of animal disease models exploring the application effects of recombinant collagen in wound hemostasis, wound repair, corneal therapy, female pelvic floor dysfunction (FPFD), vaginal atrophy (VA) and vaginal dryness, thin endometritis (TE), chronic endometritis (CE), bone tissue regeneration in vivo, cardiovascular diseases, breast cancer (BC) and anti-aging. The mechanism of action of recombinant collagen in the treatment of FPFD and CE was introduced, and the clinical application and curative effect of recombinant collagen in skin burn, skin wound, dermatitis, acne and menopausal urogenital syndrome (GSM) were summarized. From the exploratory studies and clinical applications, it is evident that recombinant collagen has demonstrated surprising effects in the treatment of all types of diseases, such as reducing inflammation, promoting cell proliferation, migration and adhesion, increasing collagen deposition, and remodeling the extracellular matrix. At the end of the review, the challenges faced by recombinant collagen are summarized: to develop new recombinant collagen types and dosage forms, to explore the mechanism of action of recombinant collagen, and to provide an outlook for the future development and application of recombinant collagen.

The accumulation of uremic toxins such as urea nitrogen, blood creatinine, and uric acid of patients with renal failure in vivo would lead to aggravated kidney damage. In this study, coated aldehyde oxy-starch (CAO) was used as an adsorbent to investigate its in vitro adsorption performance on renal failure indexes for urea, indoxyl sulfate (INS), monomethylamine (MMA), dimethylamine (DMA), uric acid (UA), and creatinine (Cr). The effects of variables such as pH, temperature, concentration, dosage, and time on the adsorption capacity of CAO were systematically investigated, employing analytical techniques of high-performance liquid chromatography (HPLC) and gas chromatography (GC). The results revealed that CAO exhibited a strong adsorption capacity for urea, INS, and MMA, alongside a moderate adsorption capacity for DMA, UA, and Cr. The adsorption kinetics and thermodynamic studies indicated that the adsorption of urea and UA by CAO were fitted in pseudo-first-order kinetics, and the adsorption isotherm aligned with the Freundlich adsorption model. The enthalpy change ΔH of urea in adsorption was in the range of 40 to 60 kJ·mol^-1, which demonstrated the presence of strong adsorption force due to the interactions of coordinating groups. The ΔH of UA was greater than 80 kJ·mol^-1, indicating the generation of chemical bonds during the adsorption. Both of them, Gibbs free energy ΔG was less than 0, within the range of -20 to 0 kJ·mol^-1, suggested that the adsorption of urea and UA by CAO occurred spontaneously as physical adsorption process. The adsorption entropy ΔS of urea and UA was > 0, which indicated an increase in entropy throughout the adsorption. The infrared spectroscopygram showed the formation of a chemical bond, specifically the imine bond, following the adsorption of urea by CAO, thereby indicating a chemical reaction during the adsorption. This study elucidates the adsorption mechanism of CAO on various indexes of renal failure, providing a scientific basis for its clinical usage.

ObjectiveTo investigate the application of endoscopy in obtaining the great saphenous vein （GSV） during coronary artery bypass grafting （CABG） and explore the learning curve， with a particular focus on common challenges encountered during the learning process and their impact on early clinical outcomes. MethodsA retrospective analysis was conducted on clinical data from 83 patients who underwent off-pump CABG with endoscopic GSV harvesting at the First Affiliated Hospital of Zhengzhou University from July 2013 to April 2014. Patients were categorized into four groups based on the chronological order of their hospitalization： Group A （novice group， n=20）， Group B （proficient group， n=20）， Group C （progressive group， n=20）， and Group D （mature group， n=23）. Differences in perioperative and midterm follow-up outcomes among the groups were analyzed to determine the learning curve period. ResultsThe study population had a mean age of （60.22±8.06） years and a mean body weight of （69.77±11.66） kg. Comorbidities included hypertension （24 cases）， diabetes （26 cases）， and subacute cerebral infarction （14 cases）. The novice group exhibited significantly shorter GSV length-to-harvest time ratio relative to the other three groups （P<0.001） and a significantly higher incidence of main vein damage （P=0.006）. However， there was no statistically significant difference in graft patency at the 1-year follow-up. ConclusionThorough and reliable technical training in endoscopic GSV harvesting is essential to minimize vascular injury caused by novice operators. Approximately 20 cases of hands-on experience and a careful self-analysis of procedural challenges are likely required to achieve proficiency in GSV harvesting.

Hyperkalemia is one of the common ion metabolism disorders in clinical practice. Hyperkalemia is defined as serum potassium higher than 5.0 mmol/L according to the guidelines at home and abroad. Acute severe hyperkalemia can cause serious consequences, such as flaccid paralysis, fatal arrhythmia, and even cardiac arrest. The use of renin-angiotensin- aldosterone system inhibitors, β-blockers and diuretics, low-sodium and high-potassium diets, and the presence of related comorbidities increase the occurrence of hyperkalemia. Hyperkalemia risk exist in all clinical departments, but there is a lack of a standardization in the management of multi- department cooperation in hospital. Therefore, a number of domestic nephrology and cardiology department experts have discussed a management model for multi-department cooperation in hyperkalemia, formulating the management standard on hospital evaluation, early warning, diagnosis and treatment, and process. This can promote each department to more effectively participate in nosocomial hyperkalemia diagnosis and treatment, as well as the long-term management of chronic hyperkalemia, improving the quality of hyperkalemia management in hospital.

BACKGROUND:Grape seed extract has been shown to be effective in inhibiting the growth of androgen-dependent tumors(e.g.,breast cancer),and thus grape seed extract could theoretically inhibit epiphyseal closure induced by estrogen in late adolescence. OBJECTIVE:To screen the effects of grape seed extract on apoptosis of growth plate chondrocytes and epiphyseal closure in rats. METHODS:(1)In vitro experiment:Growth plate chondrocytes from rat large tibia and femur at logarithmic growth stage were obtained and cultured in groups:normal control group,model control group(adding 17β-estradiol to induce apoptosis),positive control group(adding letrozole and 17β-estradiol),grape seed extract group(adding 17β-estradiol and 10 μg/mL grape seed extract),Caspase-9 inhibitor group(adding 17β-estradiol and Caspase-9 inhibitor),Caspase-9 agonist group(adding 17β-estradiol and Caspase-9 agonist).Cell apoptosis was detected by flow cytometry after 48 hours of culture.(2)In vivo experiment:Thirty 3-month-old Sprague-Dawley rats were randomly divided into model control group,positive control group and low-,medium-and high-dose groups,with five rats in each group.All rats were injected subcutaneously with 17β-estradiol(3 times per week)to establish epiphyseal closure models,followed by intragastric administration of letrozole in positive control group and 0.05,0.2 and 0.8 g/kg grape seed extract in low-,medium-and high-dose groups,respectively,once a day until over 2/3 of the epiphyseal plate in the model control group was closed.The length of the tibia was then observed.Another 18 Sprague-Dawley rats were randomly divided into model control group,positive control group,and medium-dose group,with 6 rats in each group,treated as above for 1.5 continuous months.The expression of Caspase-9 protein in rat growth plate cartilage was detected by western blot. RESULTS AND CONCLUSION:(1)In vitro experiment:17β-estradiol could induce apoptosis in growth plate chondrocytes,and letrozole,grape seed extract,and caspase-9 inhibitors could all inhibit apoptosis in growth plate chondrocytes.(2)In vivo experiment:When more than 2/3 of the epiphyseal plate in the model control group was closed,the number of rats with epiphysis closure in the positive control and medium-dose groups was less than that in the model control group(P＜0.05),and the tibial length was longer than that in the model control group(P＜0.05),and the Caspase-9 protein expression in the tibial growth plate was lower than that in the model control group(P＜0.05).To conclude,the appropriate dose of grape seed extract can effectively inhibit the apoptosis of growth plate chondrocytes and delay epiphyseal closure,which has the potential to promote bone growth.

Objective:To introduce the experience of reconstructing the pelvic floor with a pedicled large omental flap combined with a basement membrane biological mesh in combined pelvic organ resection for locally advanced or locally recurrent rectal cancer combined with sacrococcygeal resection, and to discuss the feasibility, safety, and near-term therapeutic efficacy of this technique.Methods:For patients with sacrococcygeal resection of combined pelvic organs, a basement membrane mesh was used to rebuild the pelvic floor with a pedicled greater omentum flap to isolate the abdominopelvic cavity. The main operation was to pull the greater omentum, which preserved the double vascular arches, to the pelvic floor to cover the pelvic floor, and then the mesh was used to cover the posterior peritoneal defect and pelvic inlet with absorbable sutures of 2-0 or thicker.Results:In this study, a retrospective cohort study was used to collect clinical data through the China Rectal Cancer Combined Pelvic Organs Resections Case Database. Twenty patients with locally advanced or locally recurrent rectal cancer without extra-pelvic metastasis or only oligometastases underwent combined pelvic organ and sacrococcygeal resection in the Department of Anal and Intestinal Surgery of the Second Affiliated Hospital of the Naval Military Medical University during the period of July 1, 2022, to June 30, 2023, and 10 patients underwent simple basement membrane resection with a simple basement membrane. Among them, the pelvic floor were reconstructed by basement membrane mesh alone in 10 cases (mesh only group), and 10 cases were reconstructed the pelvic floor by pedicled large omental flap combined with basement membrane mesh (omental flap-combined mesh group). The recent outcomes of the two groups of patients were studied comparatively. Comparison of baseline data and intraoperative conditions between the two groups showed no statistically significant differences (all P>0.05); the drain removal time in the omental flap-combined mesh group was 26.7 (19-42) days, which was shorter than that in the mesh only group, which was 40.4 (24-56) days ( U=4.125, P=0.001); The empty pelvis healing time in the omental flap-combined mesh group was 29.4 (23~43) days, which was shorter than that of 42.2 (27~58) days in the mesh-only group ( U=4.043, P=0.001); the differences were all statistically significant. The postoperative complication rate of grade ≥III in the omental flap-combined mesh group was 1/10, which was lower than that of 6/10 in the mesh-only group; the difference was not statistically significant when comparing the two groups ( P = 0.057). Follow-up ended on 09/30/2023, with a median follow-up of 9.5 (3-15) months in 20 patients, and all 20 cases survived during the follow-up period, with no tumor recurrence at the surgical site. Conclusion:In locally advanced or locally recurrent rectal cancer undergoing combined pelvic organ resection with sacrococcygeal, compared with reconstruction of the pelvic floor by basement membrane mesh alone, reconstruction of the pelvic floor and isolation of the abdominopelvic cavity by a pedicled greater omentum flap combined with a basement membrane mesh is safe and feasible.

Objective To establish the finite element model of spinal canal reconstruction and internal fixation,analysis influence of spinal canal reconstruction and internal fixation on spinal stability,and verify the effectiveness and reliability of spinal canal reconstruction and internal fixation in spinal canal surgery.Methods A 30-year-old male healthy volunteer with a height of 172 cm and weight of 75 kg was selected and his lumbar CT data were collected to establish a finite element model of normal lumbar Lo3-L,and the results were compared with in vitro solid results and published finite element analysis results to verify the validity of the model.They were divided into normal group,laminectomy group and spinal canal reconstruction group according to different treatment methods.Under the same boundary fixation and physiological load conditions,six kinds of ac-tivities were performed,including forward bending,backward extension,left bending,right bending,left rotation and right rota-tion,and the changes of range of motion(ROM)of L3-L4,L4-L5 segments and overall maximum ROM of L3-L5 were analyzed under the six conditions.Results The ROM displacement range of each segment of the constructed L3-L5 finite element model was consistent with the in vitro solid results and previous literature data,which confirms the validity of the model.In L3-L4,ROM of spinal canal reconstruction group was slightly increased than that of normal group during posterior extension(＞5％dif-ference),and ROM of other conditions was similar to that of normal group(＜5％difference).ROM in laminectomy group was significantly increase than that in normal group and spinal canal reconstruction group under the condition of flexion,extension,left and right rotation.In L4-L5,ROM in spinal canal reconstruction group was similar to that in normal group(＜5％differ-ence),while ROM in laminectomy group was significantly higher than that in normal group and spinal canal reconstruction group(＞5％difference).In the overall maximum ROM of L3-L5,spinal canal reconstruction group was only slightly higher than normal group under the condition of posterior extension(＞5％difference),while laminectomy was significantly higher than normal group and spinal canal reconstruction group under the condition of anterior flexion,posterior extension,left and right rotation(＞5％difference).The changes of each segment ROM and overall ROM of L3-L5 showed laminectomy group＞spinal canal reconstruction group＞normal group.Conclusion Laminectomy could seriously affect biomechanical stability of the spine,but application of spinal canal reconstruction and internal fixation could effectively reduce ROM displacement of the responsi-ble segment of spine and maintain its biomechanical stability.

Objective To analyze the hip joint biomechanies of the acetabular anatomical reconstruction and nonanatomi-cal reconstruction in total hip arthroplasty(THA)for Crowe type Ⅲ developmental dysplasia of the hip(DDH)by finite ele-ment method,which provided theoretical foundation and experimental basis for the anatomical acetabular reconstruction dur-ing THA in clinical practice.Methods One patient with left end-stage hip arthritis secondary to Crowe type Ⅲ DDH was se-lected in this study,who underwent total hip arthroplasty in the orthopedic department of the First Affiliated Hospital of Bengbu Medical College in April 2020.This patient was female,57 years old.The preoperative and postoperative three dimentional CT scan of the patient's pelvis were performed.Fourteen acetabular cup models with different anteversion,inclination and rotation center height were established in Mimics and 3-Matic software.The boundary and load conditions were set in Abaqus software.The Von Mises and stress distribution of the hip joint were calculated and observed.Results In the Crowe type Ⅲ DDH THA,if the hip rotation center was restored anatomically and the acetabular cup's inclination was set as 40°,the cup's anteversion var-ied from 5° to 25°,the lowest Von Mises value of acetabular cup and polyethylene liner occured in 20°anteversioin;if the hip rotation center was restored anatomically and the acetabular cup's anteversion was set as 15°,the cup's inclination varied from 35° to 55°,the lowest Von Mises value of acetabular cup and polyethylene liner occured in 35° inclination;if the acetabular cup's anteversion and inclination were set as 15°and 40°respectively,the up migration of hip rotaion center varied from 0 mm to 20 mm,the lowest Von Mises value of acetabular cup and polyethylene liner occured in 10 mm up migration.In all fourteen models,the Von Mises value of the acetabulum,acetabulum cup and polyethylene liner were lowest when the acetabular cup's anteversion and inlcination were 15°,35° respectively,as well as the rotation center was restored anatomically.Conclusion In total hip arthroplasty for Crowe type Ⅲ DDH,the anatomical restoration of hip rotation center with 15° anteversion and 35° in-clination of the acetabular cup are suggested,bone graft above the acetabular cup and additional screws are recommended si-multaneously to further reduce the Von Mises of hip joint.

Objective To investigate the clinical efficacy of mitral valve repair technique in the treatment of rheumatic mitral valve lesions. Methods The clinical data of patients diagnosed with rheumatic mitral valve lesions and undergoing mitral valve repair under extracorporeal circulation in our department from 2021 to 2022 were retrospectively analyzed. Results A total of 100 patients were collected, including 78 females and 22 males with an average age of 52 years. There were no secondary open heart or death in the whole group. Extracorporeal circulation time was 136.3±33.1 min, aortic cross-clamping time was 107.6±27.5 min, ventilator use time was 12.9±5.9 h, ICU stay was 2.6±1.4 d, and vasoactive medication use was 823.4±584.4 mg. Before and after the surgery, there were statistical differences in the left ventricular end diastolic diameter, left atrial end systolic diameter, effective mitral valve orifice area, shortening rate of left ventricular short axis, mitral E-peak blood flow velocity, mean mitral transvalvular pressure difference, mitral pressure half-time, and cardiac function graded by New York Heart Association (P＜0.05). While there was no statistical difference in left ventricular ejection fraction or left ventricular end-diastolic volume (P>0.05). Conclusion Overall repair of rheumatic mitral valve lesions can significantly improve the cardiac function and hemodynamics of the patients, and is a good choice for patients with rheumatic mitral valve lesions.

Objective To develop a matrix metalloproteinase(MMP)-responsive hyaluronic acid(HA)-based controlled-release material for brain-derived neurotrophic factor(BDNF)to provide a novel therapeutic strategy for intervention and repair of traumatic brain injury(TBI).Methods HA was modified with amination,followed by condensation with Suflo-SMCC carboxyl group to form amide,and then linked with glutathione(GSH)to synthesize HA-GSH.The recombinant glutathione S-transferase(GST)-tissue inhibitor of metalloproteinase(TIMP)-BDNF(GST-TIMP-BDNF)expression plasmid was constructed using molecular cloning technique with double enzyme digestion by Bam H Ⅰ and Eco R Ⅰ.The recombinant GST-TIMP-BDNF protein was expressed in the Escherichia coli prokaryotic expression system,and purified by ion exchange chromatography,confirmed by Western blotting.MMP diluents were supplemented with PBS,MMP inhibitor marimastat,and varing concentrations(0.4,0.6,0.8 mg/ml)of GST-TIMP-BDNF or GST-BDNF.MMP-2 activity was analyzed using an MMP activity detection kit to evaluate the inhibitory effect of the recombinant protein on MMP.Primary rat neurons were extracted and cultured to establish an iron death model induced by RSL3.The effect of recombinant protein GST-TIMP-BDNF on neuronal injury was detected by immunofluorescence staining.Results MRI hydrogen spectrum identification confirmed the successful synthesis of HA-GSH.Western blotting results showed the successful expression of the recombinant protein GST-TIMP-BDNF containing the GST tag using the E.coli prokaryotic expression system.MMP activity detection results indicated that the recombinant protein GST-TIMP-BDNF had a superior inhibitory effect on MMP-2 activity compared to GST-BDNF(P<0.05).Immunofluorescence staining results showed a significant increase in fluorescence intensity in rat neurons treated with GST-TIMP-BDNF after RSL3 induction(P<0.05).Conclusion A MMP-responsive HA-based BDNF controlled-release material has been successfully developed,exhibiting a protective effect on neuron damage.