BACKGROUND:Methicil in-resistant Staphylococcus aureus has been a primary pathogen of nosocomial infections worldwide. To construct a quick and easy knockout method is an important technique of studying virulence and resistance of methicil in-resistant Staphylococcus aureus. OBJECTIVE:To construct the Staphylococcus aureus gene knockout plasmid for understanding the antibiotic resistance and virulence of Staphylococcus aureus. METHODS:pUC19 was considered as a basic skeleton of construction. pLE194Ts temperature-sensitive replicon and tetracycline resistance gene fragment pHY300PLK plasmid in pCL52.1 were bound to EcoR I site in pUC19 by high assurance amplification. Al multiple clone sites in pUC19 were reserved. The Escherichia coli-Staphylococcus aureus shuttle plasmid was obtained. The N315 dapB gene knockout plasmid was obtained through gene knockout technology. This strain was eventual y identified by multiplex-PCR. RESULTS AND CONCLUSION:The Escherichia coli-Staphylococcus aureus shuttle plasmid, pYZ1 and pYZ8, was successful y constructed, and had been used in Staphylococcus aureus gene knockout. Homologous recombinant plasmid pYZ-ΔdapB was constructed by restriction enzyme digestion and overlap technique. After genetical y modification in RN4220, the constructed gene knockout plasmid pYZ-ΔdapB was introduced to N315 to be screened in the low culture temperature. The deletion strain was successful y obtained after being identified by multiplex-PCR. Above data suggested that pYZ1 and pYZ8 can be successful y used for Staphylococcus aureus gene detection, which provides a tool to study resistance and virulence of clinical Staphylococcus aureus strains.

BACKGROUND:Methicil in-resistant Staphylococcus aureus (MRSA) infection had been a global problem up to 1980s, and it has become a leading pathogen giving rise to nosocomial infections now.
OBJECTIVE:To determine the molecular types and drug susceptibilities of Staphylococcus aureus prevailed in burn ward, and to provide a basis for preventing and control ing MRSA intections.
METHODS:A total of 53 Staphylococcus aureus strains were col ected from the burn ward in the Urumqi General Hospital of Lanzhou Military Region of Chinese PLA. These MRSA strains were identified by PCR and cefoxitin disc diffusion test, and al MRSA strains were typed by spa, SCCmec and MLST typing. In the meanwhile, antibiotic susceptibilities of 17 kinds of drugs, such as oxacil in, to Staphylococcus aureus were also determined, and drug resistance of different types of Staphylococcus aureus especial y MRSA, was analyzed.
RESULTS AND CONCLUSION:Among 53 Staphylococcus aureus strains, 43 were identified as MRSA, containing determined for amplification of meoA (n=41) and positive for cefoxitin disc diffusion test (n=2). Three SCCmec types, four spa types, and three ST types were found. The major predominant clone was ST239-MRSA-III-t030 (90.7%), with highest resistant to oxacil in and other nine antibiotics. In conclusion, the higher MRSA isolation rate from the burn ward, and ST239-MRSA-III-t030, as the predominant clone, presents with an outbreak in the burn ward and stronger resistance to many different families of antibiotics.

BACKGROUND:Brahma-related gene 1 (Brg1), a catalytic subunit of an important chromatin remodeling complex, has been considered as a key nuclear transcriptional factor, and tends to be decreased in diabetic cardiomyopathy.
OBJECTIVE:To construct an adenovirus vector carrying Brg1, and observe its protective role in oxidative stress induced-cardiomyocyte apoptosis.
METHODS:The recombinant adenovirus plasmid was linearized and transfected into HEK293 cel s using Fugene HD for packaging and amplification. The adenovirus particles were further purified, quantified, and sequential y transfected to cardiomyocytes of neonatal Sprague-Dawley rats. The Adeno-EGFP transfected and non-transfected cardiomyocytes were used as control group. 24 hours later, the transfection efficiency was observed by fluorescent microscope, and expressions of Brg1 mRNA and protein were detected by quantified PCR and western blotting. After treatment with 100 μmol/L H2O2 for 12 hours, the expressions of Brg1 protein and cleaved-Caspase 3 were measured by western blotting, and cel apoptosis was analyzed by flow cytometry.
RESULTS AND CONCLUSION:(1) The recombinant adenovirus vector of Brg1 had been successful y transfected into cardiomyocytes with higher expressions of Brg1 mRNA and protein, and the transfection efficiency reached more than 90%. (2) After H2O2 treatment, the Brg1 was significantly down-regulated in contrast to the up-regulation of cleaved-Caspase 3;the flow cytometry data showed that the apoptotic cel s were increased. But in Adeno-Brg1 transfected cardiomyocytes, the H2O2 induced cel apoptosis was significantly decreased compared with non-transfected cel s and empty vector transfected cel s. (3) These results suggest that oxidative stress can directly inhibit the Brg1 expression, and overexpression of Brg1 can protect the cardiomyocytes from cel apoptosis induced by oxidative stress.

Objective To explore the application of unmanned aerial vehicles (UAVs) technology for casualty evacuation in disaster rescue.Methods The research status of casualty evacuation using unmanned aerial vehicles was described in the disaster medical rescue,and several UAVs involved in casualty evacuation were introduced.According to different dynamic structures,casualty evacuation UAVs were divided into four types,such as traditional rotor helicopter,multi-rotor aircraft,ducted fan aircraft,compound aircraft.Meanwhile,the load capacity and flight speed of involved UAVs were analyzed.Results The advantages of casualty evacuation UAVs in the previous researches related were summarized,with the problems and technical difficulty discussed.Furthermore,the development tendencies of casualty evacuation UAVs were predicted.Conclusion Casualty evacuation UAVs can transport the wounded to the professional medical institutions outside of the disaster scene instead of rescue crews,to reduce the casualty rate of rescuers and avoid secondary damage of the injured personnel,with accurate point to point casualty evacuation.

OBJECTIVETo study the effects of dosages of total body irradiation on the healing process of cutaneous wounds and to observe the changes of wound area at different periods after injury.

METHODSThe entire body irradiation from a (60)Co gamma-ray source was performed on Wistar rats. The single dosage varied from 1 to 8 Gy. Within 1 h after irradiation, two whole thickness circular cutaneous wounds corresponding to 2.5% of total body surface area (Phi = 22 mm) were produced on the back of the animals (combined injury groups). Same wounds were produced on rats with no irradiation (single wound group). Wound healing was observed at different points after injury.

RESULTSAfter total body irradiation with the dose of 1, 2, 3, 4, 5, 6, 7 or 8 Gy, the wound healing was obviously retarded as the dosages increased. The wound area remained was larger in the large dosage groups than in the small dosage groups. Seven days after injury, there was 33.5% wound surface left unhealed in the single wound group, whereas in the combined injury groups, 35.4%, 38.1%, 41.6%, 48.8%, 53.9%, 63.7%, 69.2% and 73.9% of the wound surfaces remained unhealed, respectively. Statistical analysis showed marked correlations between the various times after total body irradiation and various dosages to the percentage of unhealed wound surface. Nine dose-effect relation formulae were deduced according to the statistical results.

CONCLUSIONSIn soft tissue trauma combined with radiation injury, the delay of wound healing is related to the dose of radiation inflicted. It is also related to the time between injury and time of observation.

Animals ; Dose-Response Relationship, Radiation ; Female ; Male ; Rats ; Rats, Wistar ; Time Factors ; Whole-Body Irradiation ; Wound Healing ; radiation effects

Background and Aims:The repair of giant incisional hernia is challenging,as closing the significant defect in the abdominal wall can lead to life-threatening complications like abdominal compartment syndrome(ACS).Botulinum toxin type A(BTA)can temporarily relax the abdominal wall muscles,facilitating defect repair,while preoperative progressive pneumoperitoneum(PPP)can increase intra-abdominal volume,reducing intra-abdominal pressure caused by hernia content reintegration.Combining BTA with PPP for the preoperative preparation of giant incisional hernia repair may have a complementary effect.This study was conducted to evaluate the clinical value of combining BTA and PPP in the repair of giant abdominal incisional hernia. Methods:The clinical data of 213 patients with giant abdominal incisional hernia treated at the Sixth Affiliated Hospital of Sun Yat-sen University from December 2015 to December 2019 were retrospectively analyzed.Two weeks after receiving combined BTA and PPP treatment,changes in bilateral abdominal wall muscle,intra-abdominal adhesions,abdominal circumference,abdominal cavity volume,and hernia sac volume ratio were assessed using CT.Intraoperative details,incidence of complications,and postoperative follow-up outcomes were recorded. Results:Following combined BTA and PPP treatment,CT scan showed a significant extension of bilateral lateral abdominal wall muscles towards the midline in all 213 patients,with an average increase of 2.45(1.53-3.29)cm on the left side and 2.54(1.68-3.40)cm on the right side;muscle thickness was reduced by an average of 0.84(0.64-1.00)cm on the left and 0.82(0.62-1.05)cm on the right,the average distance between viscera and the abdominal wall increased to(7.52±1.78)cm,with a mean increase of 6.1(4.2-6.9)cm;the mean increase in abdominal cavity volume was 1 802(1 494.98-2 316.26)mL,and the hernia sac volume ratio decreased by an average of 9％(6％-12％),all changes were statistically significant(P＜0.05).Post-PPP CT scan revealed no abdominal adhesions in 18 patients(8.45％),while 195 patients(91.55％)had varying degrees of adhesions,including 39 cases(18.31％)of sheet adhesions and 156 cases(73.24％)of mixed adhesions.Adhesions mainly consisted of omentum and intestinal tissues in 59.15％of cases.There were 43 cases(20.19％)of grade Ⅰ complications during the BTA-PPP process,including abdominal pain(28 cases),shoulder pain(9 cases),subcutaneous emphysema(6 cases),and dyspnea(3 cases).Dyspnea improved with oxygen therapy,while other complications required no special intervention.All 213 patients successfully underwent laparoscopic incisional hernia repair without conversion to open surgery or organ resection for volume reduction.Fascial closure was achieved in 209 cases(98.12％),with 4 cases(1.88％)having incomplete defect closure.The average time for adhesiolysis was 28(11.00-44.50)min,with a total operative time of 178.0(132.50-255.00)min and an average blood loss of 20(10-30)mL.The median intra-abdominal pressure(IAP)after operation was between 10 mmHg(9.00-12.00 mmHg),Among them,47 cases(22.07％)had IAP exceeding 12 mmHg,and after implementing proactive measures such as diuresis and diachoresis to reduce intra-abdominal contents,the IAP in these patients decreased to below 12 mmHg.No severe complications such as skin flap necrosis or ACS were observed.There were no deaths within postoperative 30 d,and during a follow-up period of 26(16.50-33.00)months,13 cases(6.10％)had surgical site events,including infections in 5 cases(2.35％),seromas in 7 cases(3.29％),and hematoma in 1 case(0.47％),with no hernia recurrence. Conclusion:The combination of BTA and PPP not only aids in identifying abdominal wall adhesion areas,improving preoperative surgical planning and enhancing surgical safety,but also significantly increases abdominal cavity volume and extends lateral abdominal wall muscles,facilitating the closure of giant incisional hernia defects and reducing the incidence of severe postoperative complications like ACS.This approach is worthy of clinical promotion.