Objective:To evaluate the efficacy and safety of transepithelial photorefractive keratectomy (Trans-PRK) combined with accelerated corneal cross-linking (CXL) for refractive error in patients with thin or irregular corneas, excluding keratoconus.Methods:An observational case series study was performed.Fifty-five right eyes of 55 myopic patients diagnosed with thin or irregular corneas, who underwent Trans-PRK combined with prophylactic CXL surgery, were included at Baotou Chaoju Eye Ophthalmic Hospital from August 2017 to July 2018.Uncorrected distance visual acuity (UDVA) of the operated eye was measured using international standard visual acuity charts, and refractive diopters were measured by computer and comprehensive refraction before surgery and at 1 week, 1, 3, 6, and 12 months after surgery.Corneal morphology was assessed with the Pentacam anterior segment analyzer before surgery and at 3, 6, and 12 months after surgery.Intraocular pressure (IOP) was measured with a non-contact tonometer before surgery and at 1, 3, 6, and 12 months after surgery.The incidence of postoperative complications was recorded.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Baotou Chaoju Ophthalmic Hospital (No.btcj-u-1). Written informed consent was obtained from each subject.Results:Preoperative, 1-week, 1-, 3-, 6-, and 12-month postoperative UDVA (LogMAR) were 0.52(0.55, 0.78), 0.22(0.12, 0.17), 0.10(0.04, 0.07), 0.00(-0.04, -0.16), -0.08(-0.05, -0.03) and -0.08(-0.06, -0.04), respectively, showing a statistically significant overall difference ( Z=249.44, P<0.001). UDVA at each postoperative time point was improved compared to preoperative, and UDVA at 3, 6, and 12 months postoperatively was significantly improved compared to 1 week and 1 month postoperatively (all at P<0.001). The spherical diopter at each postoperative time point decreased significantly compared to preoperative, with the spherical diopter at 1, 3, 6, and 12 months postoperatively being lower than that at 1 week postoperatively, and the 12-month postoperative spherical diopter being lower than that at 3 and 6 months postoperatively, showing statistically significant differences (all at P<0.001). The cylindrical degree at 1, 3, 6, and 12 months postoperatively was lower than that at preoperative and 1 week postoperatively, with statistically significant differences (all at P<0.05). After the operation, the spherical equivalent of the operated eye gradually decreased with time, tending toward emmetropia.The spherical equivalent at each postoperative time point decreased compared to preoperative, with the spherical equivalent at 1, 3, 6, and 12 months postoperatively being lower than that at 1 week postoperatively, and the spherical equivalent at 12 months postoperatively being lower than that at 3 and 6 months postoperatively, showing statistically significant differences (all at P<0.001). The corneal K1 and K2 values at 3, 6, and 12 months postoperatively were significantly lower than preoperatively (all at P<0.001), and the corneal K1 and K2 values at 3 months postoperatively tended to stabilize.The IOP of the operated eye at 3, 6, and 12 months postoperatively was significantly lower than preoperatively, and the IOP at 6 and 12 months postoperatively was lower than that at 1 and 3 months postoperatively, with statistically significant differences (all at P<0.001). One eye developed grade 0.5 corneal haze at 1 week postoperatively, which spontaneously resolved to transparency at 1 month postoperatively. Conclusions:Trans-PRK combined with accelerated CXL has good efficacy, stability and safety for refractive error patients with thin or irregular corneas, except for keratoconus.

Objective:To analyze the clinic effects of arthroscopic partial trapeziectomy and suture button suspensionplasty in the treatment of first carpometacarpal joint (CMCJ) Eaton stage II/III arthrosis.Methods:A retrospective study was conducted on a total of 15 cases (16 hands) of patients including 5 males (1 bilateral) and 10 females with CMCJ stage II/III arthrosis who underwent surgical treatment at the first affiliated hospital of Shenzhen university from January 2020 to June 2022, with mean age of 56.7±6.4 years (range, 46-75 years). The duration from pain to treatment was 7.8±3.2 months (range, 4-14 months). X-ray showed narrowing of CMCJ with osteophytes and distal radial subluxation. All the patients were treated with arthroscopic partial trapeziectomy and suture button suspensionplasty. The preoperative and last postoperative follow-up radiographs, visual analogue scale (VAS), thumb's Kapandji scores, disabilies of the arm, shoulder, and hand (DASH) scores, grip and pinch strength and time to return to work were compared.Results:All cases were followed up for 19.6±6.3 months (range, 11-36 months). The postoperative X-ray showed all the CMCJs were reduced with a normal height of first metacarpal. The mean time for patients to return to their daily activities was 18.69±3.70 d and the mean time to return to work was 24.63±4.91 d. The average VAS score decreased from 6.56±1.15 preoperatively to 1.00 (0.75, 1.25). The preoperative Kapandji's score was 8.00±0.82 and the postoperative Kapandji's score was 8.00 (7.25, 9.00). The average DASH values improved from 24.06±3.19 to 4.00 (3.00, 5.00). The were significant differences except for Kapandji score ( Z=-4.905, P<0.001; Z=-0.121, P=0.905; Z=-4.846, P<0.001). The mean grip and pinch strength showed improvement from an average of 16.4 (14.13, 18.68) kg and 1.70±0.35 kg to 26.14±3.27 kg and 3.58±0.91 kg with significant difference ( Z=-4.617, P<0.001; t=-7.669, P<0.001). Conclusion:Arthroscopic partial trapeziectomy and suture button suspensionplasty is a minimally invasive surgery for the treatment of first CMCJ Eaton stage II/III arthrosis. By this technique, the patients' existing instability and pain problems can be solved.

Objective:To investigate the surgical effect of pedicled upper lip mucosal flap in repairing nasal septal mucosal defects after rhinoplasty.Methods:A retrospective analysis was performed from January 2016 to October 2022, the clinical data of patients with nasal septal mucosal defects after rhinoplasty were collected in the Department of Plastic and Aesthetic (Burn) Surgery at the Second Xiangya Hospital of Central South University. The pedicled upper lip mucosal flap was utilized for repair based on the patient’s medical history and wound condition. The pedicle of the flap was designed 1 cm adjacent to the frenulum of the upper lip, and an appropriate flap was incised based on the size of the wound, with dissection performed up to the superficial layer of the orbicularis oris muscle. The dissection establishes an upper lip tunnel that connects the gingival-buccal groove to the nasal cavity. The pedicled upper lip mucosal flap was elevated and transposed into the nasal cavity via the upper lip tunnel. The position of the flap was adjusted to ensure complete coverage and fixation of the nasal septal defect wound using 5-0 absorbable suture. The visual analogue scale (VAS) and the nasal obstruction symptom evaluation (NOSE) scale were utilized to facilitate patients’ satisfaction evaluation and assessment of nasal obstruction symptoms before surgery and at 6 months post-surgery. The VAS total score was 10 points, with higher scores indicating greater levels of patient satisfaction. The NOSE scale comprises of 5 items, each assigned a score ranging from 0 to 4, denoting absence of symptoms, very mild presence, moderate intensity, relatively severe manifestation, and highly severe indication respectively. The measurement data of VAS and NOSE scores before surgery and at 6 months post-surgery was expressed by Mean±SD, using paired t-test. The score distribution of the NOSE scale was represented by the number of cases, using Mann-Whitney U test. Results:The study included a total of 15 female patients, with an average age of (27.6±2.9) years (ranging from 23 to 33 years). Eleven cases presented with preoperative cartilage exposure, and the size of tissue defect ranged from 0.9 cm×0.5 cm to 1.5 cm×0.7 cm. Nine patients had a history of smoking. Skin grafting was performed in 9 patients, while nasal mucosal metastasis was observed in 8 patients. The dimensions of the flap varied from 4.0 cm×1.2 cm to 7.0 cm×1.5 cm. The postoperative recovery was satisfactory, with successful survival of the skin flaps and no occurrences of infection, hematoma, wound dehiscence, or flap necrosis. The average duration of follow-up was (8.2±2.1) months (ranging from 6 to 12 months). The postoperative VAS score (7.73±0.88) was significantly higher compared to the preoperative score (1.86±0.74) ( P<0.01). Additionally, the postoperative NOSE score (4.66±1.71) showed a significant decrease from the preoperative score (10.73±2.68), with a statistically significant difference ( P<0.01). Among them, after surgery items of stuffy or unbreathable nose (2 cases vs. 15 cases), nasal obstruction (1 case vs. 14 cases), and feeling that the nose was not enough to breathe during exercise or exertion (4 cases vs. 14 cases) scored≥2 points were significantly less than those before operation (all P<0.01). Conclusion:The utilization of pedicled upper lip mucosal flap in the reconstruction of severe nasal septal mucosal defects following rhinoplasty has proven to be highly effective. The postoperative satisfaction of patients is remarkably high, the ventilation function exhibits significant improvement, and no severe complications are observed.

Objective:To investigate the surgical effect of pedicled upper lip mucosal flap in repairing nasal septal mucosal defects after rhinoplasty.Methods:A retrospective analysis was performed from January 2016 to October 2022, the clinical data of patients with nasal septal mucosal defects after rhinoplasty were collected in the Department of Plastic and Aesthetic (Burn) Surgery at the Second Xiangya Hospital of Central South University. The pedicled upper lip mucosal flap was utilized for repair based on the patient’s medical history and wound condition. The pedicle of the flap was designed 1 cm adjacent to the frenulum of the upper lip, and an appropriate flap was incised based on the size of the wound, with dissection performed up to the superficial layer of the orbicularis oris muscle. The dissection establishes an upper lip tunnel that connects the gingival-buccal groove to the nasal cavity. The pedicled upper lip mucosal flap was elevated and transposed into the nasal cavity via the upper lip tunnel. The position of the flap was adjusted to ensure complete coverage and fixation of the nasal septal defect wound using 5-0 absorbable suture. The visual analogue scale (VAS) and the nasal obstruction symptom evaluation (NOSE) scale were utilized to facilitate patients’ satisfaction evaluation and assessment of nasal obstruction symptoms before surgery and at 6 months post-surgery. The VAS total score was 10 points, with higher scores indicating greater levels of patient satisfaction. The NOSE scale comprises of 5 items, each assigned a score ranging from 0 to 4, denoting absence of symptoms, very mild presence, moderate intensity, relatively severe manifestation, and highly severe indication respectively. The measurement data of VAS and NOSE scores before surgery and at 6 months post-surgery was expressed by Mean±SD, using paired t-test. The score distribution of the NOSE scale was represented by the number of cases, using Mann-Whitney U test. Results:The study included a total of 15 female patients, with an average age of (27.6±2.9) years (ranging from 23 to 33 years). Eleven cases presented with preoperative cartilage exposure, and the size of tissue defect ranged from 0.9 cm×0.5 cm to 1.5 cm×0.7 cm. Nine patients had a history of smoking. Skin grafting was performed in 9 patients, while nasal mucosal metastasis was observed in 8 patients. The dimensions of the flap varied from 4.0 cm×1.2 cm to 7.0 cm×1.5 cm. The postoperative recovery was satisfactory, with successful survival of the skin flaps and no occurrences of infection, hematoma, wound dehiscence, or flap necrosis. The average duration of follow-up was (8.2±2.1) months (ranging from 6 to 12 months). The postoperative VAS score (7.73±0.88) was significantly higher compared to the preoperative score (1.86±0.74) ( P<0.01). Additionally, the postoperative NOSE score (4.66±1.71) showed a significant decrease from the preoperative score (10.73±2.68), with a statistically significant difference ( P<0.01). Among them, after surgery items of stuffy or unbreathable nose (2 cases vs. 15 cases), nasal obstruction (1 case vs. 14 cases), and feeling that the nose was not enough to breathe during exercise or exertion (4 cases vs. 14 cases) scored≥2 points were significantly less than those before operation (all P<0.01). Conclusion:The utilization of pedicled upper lip mucosal flap in the reconstruction of severe nasal septal mucosal defects following rhinoplasty has proven to be highly effective. The postoperative satisfaction of patients is remarkably high, the ventilation function exhibits significant improvement, and no severe complications are observed.

Objective:To analyze the epidemiological characteristics of geriatric acetabular fractures in western China.Methods:A retrospective case series study was made on data of geriatric patients with acetabular fracture hospitalized in 4 grade A hospitals in western China from 2015 to 2020. The investigation content included gender, age, incidence rate, injury mechanism, combined injuries, comorbidities, fracture types and treatment plans.Results:A total of 299 geriatric patients with acetabular fractures were included, including 203 males and 96 females, aged 60-97 years [(68.6±7.6)years]. The mean age of the patients was increased from 67.5 years to 71.1 years. The incidence rate was increased from 36 cases per year to 64 cases per year. The injury mechanism was mainly traffic accidents (42.47%), followed by falls (30.44%). Thoracic injury was the most common type of combined injuries (39.81%). Hypertension was the main comorbidity (28.76%). The most common fracture type was anterior column posterior hemitransverse fracture (31.32%). Of 299 patients, 210 received surgical treatment, with the surgery rate of 70.23%.Conclusions:Geriatric acetabular fracture is characterized by gradually increased age and incidence rate, traffic accidents as the main cause of injury, thoracic injury as the main combined injury, hypertension as the main comorbidity, anterior column posterior hemitransverse fracture as the main fracture type and surgery as the main treatment option.

Objective:To investigate the clinical efficacy of wrist arthroscopic transosseous footprint repair technique for treating triangular fibrocartilage complex (TFCC) injury.Methods:A retrospective case series study was conducted to analyze the clinical data of 56 patients with TFCC injury admitted to Shenzhen Second People′s Hospital from July 2017 to September 2020, including 38 males and 18 females, aged 17-45 years [(33.5±3.6)years]. All patients had unilateral injury. Physical examination showed instability of the distal radioulnar joint, and MRI and arthroscopy confirmed deep ligament injury of TFCC. All patients underwent repair of deep insertion of the TFCC by using wrist arthroscopic transosseous footprint. The operation time, intraoperative blood loss, wound healing and postoperative complications were recorded. The flexion and extension range of motion of the wrist, radial and ulnal deviation of the wrist, rotation range of motion of the forearm, patient related wrist evaluation (PRWE) score, modified Mayo wrist score, visual analogue scale (VAS), and percentage of grip strength between the affected side and unaffected side were compared preoperatively, at 3 months postoperatively and at 1 year postoperatively.Results:All patients were followed up for 12-18 months [(13.4±5.2)months]. The operation time was (61.3±8.9)minutes, with the intraoperative blood loss of (2.4±1.2)ml. All wounds were healed by first intension. There was no wound infection or ulnar nerve irritation symptom after operation. Four patients experienced clicking on the ulnar side of the wrist in a short period of time post-operation, with spontaneous disappearance of the symptom. At 3 months postoperatively, the radial and ulnar deviation of the wrist was decreased from (52.5±5.9)° preoperatively to (42.6±5.9)°, and rotation range of motion of the forearm was decreased from (94.9±8.4)°preoperatively to (84.6±5.9)° (all P<0.01). The flexion and extension range of motion of the wrist was (93.1±17.4)° preoperatively, with insignificant difference compared with (89.4±5.8)° at 3 months postoperatively ( P>0.05). At 1 year postoperatively, the flexion and extension range of motion of the wrist, radial and ulnar deviation range of motion of the wrist, and rotation range of motion of the forearm were significantly increased to (101.3±13.6)°, (52.4±6.6)°, and (116.4±16.4)° when compared with those at 3 months postoperatively (all P<0.01). At 3 months postoperatively, the PRWE score was increased to (17.1±3.8)points from (10.6±3.2)points preoperatively ( P<0.01), modified Mayo wrist score was decreased to (70.3±6.7) points from (78.1±12.7)points preoperatively ( P<0.01), VAS was decreased to (4.4±1.7)points from (6.2±1.5)points preoperatively ( P>0.05), and percentage of grip strength between the affected side and unaffected side was decreased to (55.7±8.7)% from (74.4±15.2)% preoperatively ( P<0.01). At 1 year postoperatively, the PRWE score was increased to (2.0±0.9)points, modified Mayo wrist score was increased to (94.8±3.3)points, VAS was decreased to (2.1±1.1)points, and percentage of grip strength between the affected side and unaffected side was increased to (93.2±8.7)% when compared with those at 3 months postoperatively (all P<0.01). Conclusion:Wrist arthroscopic transosseous footprint repair technique can effectively treat deep ligament injury of TFCC, with advantages of significantly improving postoperative joint range of motion and functional score, relieving the pain on the ulnar side of the wrist and enhancing grip strength.

Objective:To investigate the role of TiRobot combined with O-arm assisted closed reduction and percutaneous screw fixation in unstable pelvic fracture surgery.Methods:Twelve patients with unstable pelvic fractures, 7 males and 5 females, aged 39.41±12.56 years (range 25-60 years), admitted from January 2020 to January 2021, were retrospectively analyzed. The duration between injury and surgery was 9.67±5.81 d (range 4-24 d). The following are the causes of injury, namely traffic injury in 6 cases, fall from height injury in 4 cases, crush injury in 2 cases. Tile type of pelvic fractures were 3 cases of type B (2 cases of type B2, 1 case of type B3), 9 cases of type C (4 cases of type C1, 3 cases of type C2, 2 cases of type C3). Sacral fractures with Denis division were 5 cases of zone I, 7 cases of zone II. Seven patients were repositioned by intraoperative traction on the injured side of the limb and maintained by fixation with a Starr frame. Two cases were repositioned by intraoperative longitudinal bone traction on each lower limb for fracture displacement. The other 3 B-type fractures were repositioned by inserting Schanz nails into the anterior inferior iliac spine bilaterally. Then, the fractures were maintained with external pelvic fixators. The fractures were assessed by O-arm fluoroscopy. Hollow screws were placed with the aid of orthopedic robotic guidance, and the screw positions were verified by O-arm fluoroscopy again after the nail placement. The duration of each screw placement and operation were recorded. The quality of fracture repositioning, hip function and postoperative complications were observed at the follow-up.Results:All patients were followed up for 8.17±1.99 months (range, 6-12 months). There were 27 screws inserted in 12 patients, with a single screw insertion duration of 19.9±1.8 min (range, 9-31 min). In all patients, one O-arm fluoroscopy was performed in each row after closed reduction and after completion of nail placement. The operative duration was 257.78±80.63 min (range, 160-450 min). The O-arm fluoroscopy after nail placement verified that 23 screws were placed in a satisfactory position at one time, with satisfactory rate of 85% (23/27) for the first nail placement. Two patients with preoperative grade II sacral plexus nerve injury recovered to grade I in one case and grade II in one case. However, the numbness was reduced after operation. No further aggravation of nerve injury occurred after surgery. The quality of fracture repositioning was evaluated according to the Matta score, including excellent in 9 cases, good in 2 cases, and acceptable in 1 case, with an excellent rate of 92% (11/12). At the last follow-up, the Majeed pelvic fracture quantitative assessment system scored 85.75±5.82 (range, 74-96). There were 8 cases in excellent and 4 cases in good. Twelve patients had one-stage wound healing. No complications, such as incision infection, nerve injury, loosening and breaking of the internal fixation occurred during the follow-up.Conclusion:TiRobot combined with O-arm assisted closed reduction and percutaneous screw fixation for unstable pelvic fractures has some advantages, including safety, precision, convenient nail placement, and less fluoroscopic radiation.

Objective:To evaluate the risk factors of acute kidney injury (AKI) in patients with multiple wasp stings.Methods:Patients with multiple wasp stings were retrospectively enrolled in Hanzhong Central Hospital from September 2010 to November 2020. Based on whether the patients developed AKI, the patients were divided into AKI group and non-AKI group. The general characteristics and laboratory examinations between the two groups were compared. The logistic regression model was used to analyze the risk factors of AKI.Results:A total of 356 patients with multiple wasp stings were recruited in this study, with 196 males (55.1%). The age was 56.0(45.0, 64.0) years old. There were 59 patients (16.6%) with hypertension and 13 patients (3.6%) with diabetes. There were 51 patients (14.3%) in the AKI group and 305 patients (85.7%) in the non-AKI group. Baseline data and biochemical examinations indicated that the two groups showed significant differences in gender, age, sting sites (systemic or local), sting needles, proportions of gross hematuria, leukocyte count, hemoglobin, creatine kinase, alanine transaminase, aspartate aminotransferase, total bilirubin, proportions of urinary protein, and proportions of urine occult blood (all P<0.05). The multivariate logistic regression analysis results showed that the increasing number of sting needles (every 10 needles increase, OR=1.866, 95% CI 1.289-2.071, P=0.001), gross hematuria ( OR=9.770, 95% CI 2.586-36.910, P=0.001), decreasing hemoglobin (every 1 g/L increase, OR=0.016, 95% CI 0.001-0.355, P=0.009), increasing aspartate aminotransferase (every 100 U/L increase, OR=1.311, 95% CI 1.144-1.502, P<0.001), and increasing total bilirubin (every 10 μmol/L increase, OR=1.200, 95% CI 1.008-1.430, P=0.041) were independent influencing factors of AKI. Conclusions:The increasing number of sting needles, gross hematuria, decreasing hemoglobin, increasing aspartate aminotransferase, and increasing total bilirubin are independent risk factors of AKI in patients with multiple wasp stings.

Objective:To evaluate the effects of weight-bearing area compression injury of the femoral head on the prognosis of elderly acetabular fractures after open reduction and internal fixation.Methods:A retrospective analysis of 36 elderly patients with acetabular fractures treated with open reduction and internal fixation during January 2014 to January 2018 were conducted. All patients with compression injury of the weight-bearing area of the femoral head, including 22 males and 14 females with 73.2±6.5 years old (range 60-87 years old), were included. The compression injury of weight-bearing area of the femoral head was not treated. According to the Letournel-Judet classification of acetabular fractures, there were 14 cases with both-column, 12 cases with anterior column and posterior hemitransverse, 4 cases with T type, 4 cases with transverse, and 2 cases with posterior column+ posterior wall. A total of 14 cases were accompanied by acetabular joint surface compression, while 29 cases were accompanied by joint dislocation. The Merle d'Aubigné score was used to evaluate the hip function during follow-up. The Matta classification method was used to evaluate the results of acetabular fracture reduction. The Kellgren-Lawrence classification standard and Ficat-Alert staging method were used to evaluate the traumatic arthritis of the hip and femoral head necrosis, respectively. During the follow-up, the femoral head necrosis with stage III, IV, or traumatic arthritis III, IV, or with indications for joint replacement was defined as surgery failure. CT scans of the pelvis were performed before and at 2-5 days after operation. The compression size of the femoral head on the coronal and axial planes of the CT scan was calculated for the compression volume. The compression severity was divided into small (<1 cm 3), medium (1-2 cm 3) and large (>2 cm 3) according to the volume. Binary Logistic regression analysis was used to analyze whether the postoperative measurement of the femoral head compression volume was associated with the risk of surgical failure. Results:All patients were followed up for 34.7±8.9 months (range 25-54 months). There were 7 cases with large compression of femoral head, 14 cases with medium, and 15 cases with small pre-operatively. However, there were 12 cases, 10 cases and 14 cases with large, medium and small at 2-5 days after operation, respectively. Six cases were excellent reduction, 22 cases were good, and 8 cases were poor. Thus, the excellent and good rate was 78% (28/36). At the last follow-up, Merle d'Aubigné score was excellent in 2 cases, good in 8 cases, fair in 5 cases, and poor in 21 cases. The excellent and good rate was 28% (10/36). There were 20 cases with surgery failure with 56% (20/36) failure rate. There were no statistically significant differences in the patient's age, body mass index, operation duration, blood volume, fracture type, fracture reduction, combined acetabular joint surface compression, and combined joint dislocation between the two groups. However, there was a statistically significant difference in the frequency distribution of compression volume in the weight-bearing area of the femoral head after surgery (χ 2=22.047, P<0.001). In patients with large, medium, and small-volume compression of the femoral head weight-bearing area, the surgery failure rates were 92%, 80%, and 7%, respectively. The large and medium-volume compression of the femoral head weight-bearing area were independent risk factors for surgical failure. Conclusion:Open reduction and internal fixation can be used to treat elderly patients with acetabular fractures combined with femoral head compression injury. Despite satisfactory reduction for acetabular fractures, the larger volume of femoral head compression affects the clinical outcomes with extremely high rate of surgical failure within 2 years.

Objective:To evaluate the relationship between the mitochondrial mechanism of diabetic mellitus-caused abolition of cardioprotection induced by ischemia postconditioning (IPO) and succinate dehydrogenase (SDH) in rats.Methods:Thirty-six SPF male non-diabetic Sprague-Dawley rats, aged 16-20 weeks, weighing about 300 g, were divided into 3 groups ( n=12 each) using a random number table method: sham operation group (ND+ Sham group), ischemia-reperfusion (I/R) group (ND+ I/R group) and IPO group (ND+ IPO group). Seventy-two rats with diabetes mellitus were divided into 6 groups ( n=12 each) using a random number table method: sham operation group (DM+ Sham group), I/R group (DM+ I/R group), DM+ IPO group, sham operation+ dimethyl malonate group (group DM+ Sham+ Dme), I/R+ dimethyl malonate group (group DM+ I/R + Dme) and IPO+ dimethyl malonate group (group DM+ IPO+ Dme). The model of cardiopulmonary bypass (CPB) was established, and the model of total I/R injury was induced by ligating the ascending aorta for 30 min followed by 60 min of reperfusion.The animals underwent 3 cycles of 30-s reperfusion followed by 30-s ischemia starting from the onset of reperfusion in each IPO group.In each Dme group, dimethyl malonate was infused through the tail vein at a rate of 4 mg· kg -1·min -1 for 40 min starting from the beginning of CPB.At the end of reperfusion, the myocardial tissues were taken for measurement of mitochondrial respiratory control ratio (RCR) (by the Lufthansa electrode method), mitochondrial membrane potential (MMP) (by the JC-1 method) and the opening of mitochondrial permeability transition pore (mPTP) (by absorptiometry) and for determination of the activity of reactive oxygen species (ROS) (with the fluorescent probe), succinate dehydrogenase (SDH) (using spectrophotometric method) and the contents of succinic acid and fumarate. Results:Compared with ND+ Sham group, the activities of SDH and ROS, opening of mPTP and content of fumarate were significantly increased, and MMP, RCR and succinic acid content were decreased in ND+ I/R ( P<0.05). Compared with group ND+ I/R, the activities of SDH and ROS, opening of mPTP and content of fumarate were significantly decreased, and MMP, RCR and succinic acid content were increased in ND+ IPO ( P<0.05). Compared with group DM+ Sham, the activities of SDH and ROS, opening of mPTP and content of fumarate were significantly increased, and MMP, RCR and succinic acid content were decreased in group DM+ I/R ( P<0.05). Compared with group DM+ I/R, no significant change was found in the parameters mentioned above in group DM+ IPO ( P>0.05). Compared with group DM+ IPO, the activities of SDH and ROS, opening of mPTP and content of fumarate were significantly decreased, and MMP, RCR and succinic acid content were increased in group DM+ IPO+ Dme ( P<0.05). Compared with group DM+ I/R+ Dme, the activities of SDH and ROS, opening of mPTP and content of fumarate were significantly decreased, and MMP, RCR and succinic acid content were increased in group DM+ IPO+ Dme ( P<0.05). Conclusion:The mitochondrial mechanism of diabetic mellitus-caused abolition of cardioprotection induced by IPO may be related to the enhancement of SDH activity in rats.