[Properties of gelatin-polyethylene glycol hydrogel loaded with silver nanoparticle Chlorella and its effects on healing of infected full-thickness skin defect wounds in mice].

Objective: To explore the properties of gelatin-polyethylene glycol hydrogel loaded with silver nanoparticle (AgNP) Chlorella (hereinafter referred to as the composite hydrogel) and its effects on healing of infected full-thickness skin defect wounds in mice. Methods: The research was an experimental research. The simple gelatin-polyethylene glycol hydrogel (hereinafter referred to as the simple hydrogel) and the composite hydrogel were prepared, and the appearance and injectability of the two hydrogels were observed at 55 and 37 ℃, and under the irradiation of 808 nm near-infrared light, respectively. An electronic universal testing machine was employed to assess the tensile and compressive stress-strain properties of both types of hydrogels at room temperature. Additionally, the cyclic compressive stress-strain properties of the composite hydrogel were examined at 80% of the maximum compressive stress. Staphylococcus aureus or Escherichia coli solution was added to phosphate buffer solution (PBS), simple hydrogel, and composite hydrogel, respectively. The part of composite hydrogel containing Staphylococcus aureus or Escherichia coli solution was irradiated with near-infrared light for 5 minutes. After each sample was incubated for 6 h, the dilution plating method was used to detect and calculate the mortality rates of the two bacteria at 24 h of culture (n=5). The discarded foreskin tissue was taken from a 6-year-old healthy boy admitted to the Department of Urology of the First Affiliated Hospital of Naval Medical University for circumcision. Primary human fibroblasts (HFbs) were isolated using the enzyme extraction method, routinely cultured to the 3rd to 6th passages for subsequent cellular experiments. Composite hydrogel extracts with final mass concentrations of 100.0, 50.0, 25.0, 12.5, and 0 mg/mL were respectively prepared and used to culture HFbs, and the cell proliferation after 24 h of culture was detected using a cell counting kit 8 (n=3). A total of twenty 6-8 weeks old C57BL/6J female mice were utilized, and a full-thickness skin defect was surgically created on the back of each mouse. The wounds were infected with Staphylococcus aureus solution. The infected mice were divided into blank control group, simple hydrogel group, composite hydrogel group, and combined treatment group according to the random number table, and the wounds were treated with PBS, simple hydrogel, composite hydrogel, and composite hydrogel+light irradiation (under the irradiation of 808 nm near-infrared light for 5 min), respectively, with 5 mice in each group. On post injury day (PID) 0 (immediately after the first wound treatment), 3, 7, and 14, an overall assessment of wound exudation and healing were conducted, and the wound healing rates on PID 7 and 14 were calculated (n=5). On PID 14, hematoxylin-eosin staining was performed to observe histopathological changes in the mouse wound. Results: Both simple hydrogel and composite hydrogel were in a solution state at 55 ℃ and transition to a gel state when cooling to 37 ℃. After the two hydrogels were irradiated by near-infrared light, only the composite hydrogel reheated up and returned to the solution state again with injectability. The maximum tensile stress of the composite hydrogel was up to 301.42 kPa, with a corresponding strain of 87.19%; the maximum compressive stress was up to 413.79 kPa, with a corresponding strain of 91.67%, which was similar to the tensile and compressive properties of the simple hydrogel. After 10 compression cycles, the maximum compressive stress of the composite hydrogel still reached 84.1% of the first compressive stress. After 24 h of culture, the mortality rate of Staphylococcus aureus treated with simple hydrogel was significantly higher than that treated with PBS (P<0.05); the mortality rates of Escherichia coli and Staphylococcus aureus treated with composite hydrogel alone were significantly higher than those treated with simple hydrogel (P<0.05); the mortality rates of Escherichia coli and Staphylococcus aureus treated with composite hydrogel+light irradiation were significantly higher than those treated with composite hydrogel alone (P<0.05). After 24 h of culture, compared with that cultured in composite hydrogel immersion solution with final mass concentration of 0 mg/mL, the proliferation activity of HFbs cultured in composite hydrogel immersion solution with final mass concentrations of 25.0 and 50.0 mg/mL was significantly enhanced (P<0.05), while the proliferation activity of HFbs cultured in composite hydrogel immersion solution with final mass concentration of 100 mg/mL was significantly decreased (P<0.05). On PID 0 and 3, more purulent secretions were seen in the wounds of mice in blank control group and simple hydrogel group, while only a small amount of exudate was observed in the wounds of mice in composite hydrogel group, and no obvious infection was observed in the wounds of mice in combined treatment group. On PID 7 and 14, the wound healing rates of mice in simple hydrogel group were significantly higher than those in blank control group (P<0.05); the wound healing rates of mice in composite hydrogel group were significantly higher than those in simple hydrogel group (P<0.05); the wound healing rates in combined treatment group were significantly higher than those in composite hydrogel group (P<0.05). On PID 14, the wounds of mice in blank control group exhibited a high infiltration of inflammatory cells with no new epithelial layer observed; the wounds of mice in simple hydrogel group displayed a short length of newly formed epithelium with a small amount of inflammatory cells; the wounds of mice in composite hydrogel group exhibited continuous formation of new epithelium and a large amount of immature granulation tissue; the wounds of mice in combined treatment group showed continuous epithelialization with less immature granulation tissue. Conclusions: The prepared composite hydrogel exhibits excellent thermosensitivity, photothermal properties, and injectability, as well as excellent mechanical properties, antibacterial properties, and biocompatibility, and can promote the healing of infected full-thickness skin defect wounds in mice.

[Clinical application and related research advances of negative pressure wound therapy in wound treatment].

Wound repair has always been one of the key issues of clinical concern. In recent years, negative pressure wound therapy (NPWT) has played an increasingly active role in promoting various wound repairs, not only for the treatment of common acute and chronic wounds, but also for closure of surgical incisions, preparation of wounds before skin transplantation, fixation of skin grafts after transplantation, and treatment of some complex thoracic and abdominal trauma. This review aims to summarize the clinical application of NPWT in wound treatment and the related latest research progress, and to preliminarily discuss its future development prospects.

[Two cases of Vibrio vulnificus primary sepsis].

This article analyzed the medical records of two patients with Vibrio vulnificus primary sepsis who were admitted to the First Affiliated Hospital of Naval Medical University and reviewed the latest literature. On November 6, 2019, a 54-year-old male patient was admitted to the hospital. The patient's lower limbs were red, swollen, and painful with ecchymosis and hemorrhagic bullae after he ate freshwater products. The emergency fasciotomy was performed 3 h after admission, and the multiple organ failure occurred after operation. The patient was given up treatment 24 h after admission. On August 12, 2020, a 73-year-old male patient was admitted to the hospital. He was in shock state on admission and had hemorrhagic bullae on his right lower limb after he ate seafood. At 3 h post admission, he underwent emergency surgical exploration and amputation of right thigh. Six days later, he received negative pressure wound treatment on the stump. On the 13th day post admission, his families forgo the active treatment and he died 15 d after admission. The two cases were both failed to be diagnosed at the first time, and the disease progressed rapidly. Necrotizing fasciitis and multiple organ failure occurred. After the diagnosis was confirmed, timely fasciotomy and high amputation were performed respectively. The microbiological examinations both reported Vibrio vulnificus. Although the 2 cases were not cured successfully, the course of disease and some indexes of patient with early amputation were better than those of patients with fasciotomy. Vibrio vulnificus is widely distributed and frequently detected in fresh water products. The pathogenic pathway is fuzzy and complex, and it is easy to be misdiagnosed. It is necessary to establish the treatment process of Vibrio vulnificus sepsis. Early and aggressive surgical intervention should be carried out as soon as possible, fasciotomy and debridement should be thorough, and the patients with hemorrhagic bullae should be amputated early. Postoperative comprehensive measures are also important for improving the survival rate of patients.

[Clinical effects of negative pressure wound therapy in treating the poor healing of incisions after different abdominal operations].

Objective: To investigate the clinical effects of negative pressure wound therapy (NPWT) in treating the poor healing of incisions after different abdominal operations. Methods: The retrospective observational study was conducted. From June 2019 to December 2020, 42 patients with poor healing of incisions after abdominal surgery were admitted to Center of Burns and Trauma of the First Affiliated Hospital of Naval Medical University, including 29 males and 13 females, aged 23-81 years. The disease course of poor healing of abdominal incision was 3-60 d. The preoperative examination of patients was completed after admission, and NPWT was used after debridement. According to the dehiscence level of incision, the negative pressure value of -10.64 to -6.65 kPa was set. The incisions were sutured in the second stage when the incisions had good blood circulation. The cause of abdominal surgery, the dehiscence level and the cause of poor healing of abdominal incision were investigated, and the final healing of abdominal incision and the occurrence of complication were observed. Results: The causes of abdominal operations in this group of patients who ocurred poor healing of abdominal incisions were ranked according to the composition ratio, with the top 4 causes being colon cancer (9 cases, accounting for 21.4%), bile duct disease (8 cases, accounting for 19.0%), liver cancer (5 cases, accounting for 11.9%), and appendicitis (4 cases, accounting for 9.5%). There were 25 cases (59.5%) with dehiscence of abdominal incision in the deep fascia layer, and the other 17 cases (40.5%) with dehiscence of abdominal incision in the superficial fascia layer. The causes of poor healing of abdominal incision were ranked according to the composition ratio, with the top 3 causes being infection (24 cases, accounting for 57.1%), fat liquefaction (11 cases, accounting for 26.2%), and suture reaction (5 cases, accounting for 11.9%). The blood circulation in 40 patients was improved after being treated with NPWT, and the incisions were sutured in the second stage. The incisions healed well when the suture lines were removed in the second to third week. Intestinal fistula and bile leakage developed during the NPWT treatment, respectively in the other 2 patients, in which negative pressure equipment was removed subsequently, and the incisions healed after adequate drainage and conventional dressing changes. Conclusions: NPWT is effective in treating poor healing of abdominal incision after different abdominal surgeries. The clinicians need to comprehensively assess the patient's condition to determine when and how to use NPWT to avoid the occurrence of intestinal fistula, bile leakage, and other complications.

[Research advances on the characteristics and wound healing promoting effect of in-situ forming injectable hydrogels].

Research of in-situ induced repair and regeneration is a multi- and inter-disciplinary field, which is of important potentials in the treatment of both large-area deep burns and chronic wounds such as diabetic skin ulcers. In-situ forming injectable hydrogels which are hydrogel-like biomaterials that can spontaneously gelatinize in physiological condition when applied in local wounds have been explored in recent years. This kind of biomaterials contain extracellular matrix, in which cells promoting wound repairing can be added if required, and can work as release-controlled carriers for active peptides such as growth factors to simulate local wound microenvironment and induce the repair and regeneration. Herein, characteristics and function of promoting wound repair and regeneration about in-situ forming injectable hydrogels were reviewed, including material types and their relevant working mechanisms, advantages, existing problems, etc.

[One case of atypical septic shock with acute pulmonary edema in a patient with extensive burn].

A 25-year-old man with extensive burn due to industrial dust explosion was admitted to the First Affiliated Hospital of Naval Medical University on 16th October, 2018. Four days after the first skin grafting and vacuum sealing drainage surgery, the patient developed signs of uncontrolled severe inflammation and shock. However, several atypical manifestations interfered the diagnosis of septic shock. After giving emergency treatment including fluid resuscitation, broad-spectrum antibiotics, and administration of vasopressor agents, the patient's condition was alleviated, but quickly relapsed and deteriorated, with acute pulmonary edema appeared in the evening of the same day. Finally, the condition was reversed by completely removing the negative pressure devices on upper limbs and thorough dressing change. This case suggests that the diagnosis and treatment of infection in patients with extensive burn need comprehensive analysis. Timely intervention of the wound is the key to control the exacerbation of sepsis. In addition, the possibility of pulmonary edema in patients with sepsis should be on high alert.

[Status and challenges of tissue-engineered skin].

Autologous split-thickness skin grafting is still an important procedure for the repair of skin defect. However, there are some obvious limitations, such as new injury to skin donor sites and insufficient skin source, etc. It is an ideal goal to develop tissue-engineered skin to realize permanent replacement of skin defect. After decades of development, a variety of tissue-engineered skins have been put into the market for applications, but it is still a long way to achieve regenerative repair of skin defect. In this article, we summarize the status of various tissue-engineered skins, and then make a preliminary discussion on the opportunities and challenges on development of tissue-engineered skin.

[Clinical study of cell sheets containing allogeneic keratinocytes and fibroblasts for the treatment of partial-thickness burn wounds].

Objective: To evaluate the efficacy and safety of cell sheets containing allogeneic keratinocytes and fibroblasts in the treatment of partial-thickness burn wounds. Methods: The cell sheets containing allogeneic keratinocytes and fibroblasts were constructed using polyurethane biofilm as carrier. Then gross observation and histological observation were conducted. From April 2016 to December 2017, Changhai Hospital of Naval Medical University recruited patients with acute partial-thickness burn wounds that met the inclusion criteria for this prospective and positively self-controlled clinical trial. Recruitment of 40 acute partial-thickness burn wounds were planned with each selected single wound being not smaller than 10 cm×10 cm and not more than 5% total body surface area (TBSA). Each wound was equally divided into two areas, which were recruited into cell sheet group and conventional treatment group according to the random number table. The wounds in cell sheet group were covered by cell sheet and then sterile gauze as secondary dressings. Depending on the wound healing and exudation, the sterile gauze was replaced every 1 to 3 day (s) after the treatment was started, and the cell sheet was replaced every 7 days (namely dressing changing). The wounds in conventional treatment group were covered by sulfadiazine silver cream gauze and then dressed with sterile gauze, with the dressings changed every 2 to 3 days depending on wound exudation. On treatment day 5, 7, 10, and 14, the wound healing rates in the two groups were calculated. The complete wound healing time, the total number of dressing changes, and the status of wound infection during treatment were recorded. The Visual Analogue Scale was used to score the pain at the first dressing change. Scar formation of patients was followed up for 6 to 12 months after injury. Safety indicators including vital signs, laboratory examination indexes, and adverse reactions during treatment were observed. Data were statistically analysed with Wilcoxon rank sum test and Bonferroni correction. Results: (1) Each prepared cell sheet had a diameter of about 8 cm and was about 49 cm(2) in size, containing 2 or 3 layers of keratinocytes and fibroblasts. (2) A total of 43 patients were enrolled, of whom 3 patients dropped out of the study. Of the 40 patients who completed the treatment, there were 22 males and 18 females who were aged 1 to 57 year (s), with total burn area of 2% to 26% TBSA. (3) On treatment day 5, 7, 10, and 14, the wound healing rates in cell sheet group were significantly higher than those in conventional treatment group (Z=4.205, 4.258, 3.495, 2.521, P<0.05 or P<0.01). The complete wound healing time in cell sheet group was 7 (6, 8) days, which was significantly shorter than 11 (7, 14) days in conventional treatment group (Z=4.219, P<0.01). The total number of wound dressing changes in cell sheet group was 1 (1, 2) times, which was significantly less than 6 (4, 7) times in conventional treatment group (Z=5.464, P<0.01). (4) The wounds in cell sheet group in 31 patients healed before the first dressing change. The pain score of wounds in the first dressing change in cell sheet group of 9 patients was 1 (0, 1) point, while the pain score of wounds in the first dressing change in conventional treatment group of 40 patients was 2 (1, 3) points. There was no obvious infection in the wounds in both groups of 40 patients before the wound healing. Nine patients completed the follow-up after the trial. In 6 patients, no scar formation was observed in cell sheet group or conventional treatment group. The color of wounds in cell sheet group was consistent with normal skin, and there was only a small amount of pigment deposition in the wounds of conventional treatment group. Three patients developed pigment deposition only in the wounds of cell sheet group but obvious scars in conventional treatment group. (5) The abnormal fluctuations of vital signs including body temperature, blood pressure, heart rate, respiratory rate, and laboratory examination indexes of all patients during treatment were alleviated through the process of burn wound healing. No obvious adverse reactions or abnormalities related to the treatment were observed. Conclusions: The cell sheet containing allogeneic keratinocytes and fibroblasts can reduce the number of dressing changes, accelerate wound epithelialization, shorten wound healing time, reduce pain during dressing change in the treatment of partial-thickness burn wounds, and it may reduce scar hyperplasia after wound healing because of accelerating wound epithelization. Its clinical application is simple, safe, and effective.

[Preliminary effect observation on the application of micro-negative pressure in children with small-area deep partial-thickness burn].

Objective: To preliminarily observe the effects of application of micro-negative pressure in children with small-area deep partial-thickness burn. Methods: From January 2016 to August 2018, 64 children with small-area deep partial-thickness burn who were admitted to the Department of Burn Surgery of the First Affiliated Hospital of Naval Medical University were recruited in this prospective randomized controlled study. According to the random number table, they were divided into negative pressure group [18 boys and 14 girls, aged (3.9±1.6) years with total burn area of (5.5±2.2)% total body surface area (TBSA)] and conventional group [20 boys and 12 girls, aged (3.8±1.7) years with total burn area of (5.8±1.6)% TBSA], with 32 patients in each group. After admission, simple debridement was performed in the patients of 2 groups. After that, the children in negative pressure group were treated with micro-negative pressure with negative pressure material replaced every 3 to 5 days. Children in conventional group were treated with silver sulfadiazine cream with dressing change every other day. On post injury day (PID) 14 and 21, general wound observation was performed, the wound healing rate was calculated, the exudates from the wounds were cultured and the positive detection rate was calculated. The number of patients requiring surgical skin grafting was recorded and the rate of surgical skin grafting was calculated, and the complete wound healing time was recorded in the patients of 2 groups. Scar formation was evaluated by the Vancouver Scar Scale (VSS) in 3, 6, and 12 months after wound healing. Data were processed with chi-square test, t test, Bonferroni correction, and analysis of variance for repeated measurement. Results: (1) On PID 14, all the necrotic tissue in the wounds of patients in negative pressure group was removed, with few exudates, and most of the wounds had been epithelialized; most of necrotic tissue in the wounds of patients in conventional group was removed, with more exudates and smaller wound healing area than those in negative pressure group. On PID 21, most of the wounds of patients in negative pressure group were healed, and the exudates were rare, while the wound healing area of patients in conventional group was significantly smaller than that in negative pressure group with more exudates. (2) On PID 14 and 21, the wound healing rates [(49.8±3.3)% and (95.8±2.4)%] of patients in negative pressure group were significantly higher than those in conventional group [(40.0±3.2)% and (75.3±2.5)%, t=11.899, 33.461, P<0.01]. (3) On PID 14 and 21, the positive detection rates of wound bacteria of patients in negative pressure group were significantly lower than those in conventional group (χ(2)=6.275, 5.741, P<0.05). (4) The rate of surgical skin grafting of patients in negative pressure group was significantly lower than that in conventional group (χ(2)=5.333, P<0.05). (5) The complete wound healing time of patients in negative pressure group [(23.9±2.3) d] was significantly shorter than that in conventional group [(27.9±1.8) d, t=-7.806, P<0.01]. (6) In 3, 6, and 12 months after wound healing, the VSS scores [(6.9±1.8), (5.6±1.4), (3.4±1.5) points] of patients in negative pressure group were significantly lower than those in conventional group [(9.0±1.5), (7.4±2.0), (5.7±1.6) points, t=-4.987, -4.127, -5.988, P<0.01]. Conclusions: In comparison with routine dressing change, the treatment of application of micro-negative pressure in children with small-area deep partial-thickness burn can significantly improve the wound healing rate and rate of surgical skin grafting, decrease the wound infection rate, shorten the wound healing time, and improve the wound healing quality.

[Review of development of Department of Burn Surgery in the First Hospital of Naval Medical University over the past 60 years].

This paper briefly described the establishment and development of Department of Burn Surgery in the First Affiliated Hospital of Naval Military Medical University (the former Changhai Hospital of the Second Military Medical University) over the past 60 years. After several generations of hard work and innovative development, our department has accumulated a wealth of experience and outstanding treatment effects in the treatment of severe burn and trauma patients. We have made great achievements in clinical practice, scientific development, and talent cultivation, as well as making important contribution to the development of burn and trauma medicine in Shanghai and even in China.

[Experience of wound treatment on extremely severe mass burn patients involved in August 2nd Kunshan factory aluminum dust explosion accident].

Objective: To explore experience of wound treatment of extremely severe mass burn patients involved in August 2nd Kunshan factory aluminum dust explosion accident. Methods: On August 2nd, 2014, 98 extremely severe burn mass patients involved in August 2nd Kunshan factory aluminum dust explosion accident were admitted to 20 hospitals in China. The patients with complete medical record were enrolled in the study and divided into microskin graft group with 56 patients and Meek skin graft group with 42 patients. Split-thickness skin in area of residual skin were resected to repair wounds of patients in microskin graft group and Meek skin graft group by microskin grafting and Meek miniature skin grafting, respectively. The residual wound size on 28 days post injury and wound infection after skin grafting of patients in the two groups, and position of donor site of all patients were retrospectively analyzed. Data were processed with t test and chi-square test. Results: The size of residual wound of patients in Meek skin graft group on 28 days post injury was (59±13)% total body surface area (TBSA), which was obviously smaller than that in microskin graft group [(70±14)%TBSA, t=4.379, P<0.05]. Twenty-nine patients in microskin graft group and 11 patients in Meek skin graft group suffered from obvious wound infection after skin grafting. Wounds of patients in two groups were repaired with residual skin around wound in head, trunk, groin, armpit, and uncommon donor sites of scrotum (4 patients), vola (10 patients), and toe or finger web (8 patients). Conclusions: Meek skin graft is the first choice for wound repair of extremely severe burn mass patients, with faster wound healing, less wound infection. Uncommon donor sites of scrotum, vola, and toe or finger web can also be used for wound repair in case of lack of skin.

[Comparison of machine learning method and logistic regression model in prediction of acute kidney injury in severely burned patients].

Objective: To build risk prediction models for acute kidney injury (AKI) in severely burned patients, and to compare the prediction performance of machine learning method and logistic regression model. Methods: The clinical data of 157 severely burned patients in August 2nd Kunshan factory aluminum dust explosion accident conforming to the inclusion criteria were collected. Patients suffering AKI within 90 days after admission were enrolled in group AKI, while the others were enrolled in non-AKI group. Single factor analysis was used to choose independent factors associated with AKI, including sex, age, admission time, features of basic injuries, initial score on admission, treatment condition, and mortality on post injury days 30, 60, and 90. Data were processed with Mann-Whitney U test, chi-square test, and Fisher's exact test. Variables with P<0.1 in single factor analysis and those with possible clinical significance were brought into the establishment of prediction model. Logistic regression and XGBoost machine learning algorithm were used to build the prediction model of AKI. The area under receiver operating characteristic curve (AUC) was calculated, and the sensitivity and specificity for optimal threshold value were also calculated for each model. Nonparametric resampling test was used to compare the significance of difference of AUC of the two models. Results: (1) Eighty-nine (56.7%) patients developed AKI within 90 days from admission. Compared with 68 patients in non-AKI group, 89 patients in group AKI were older (Z=-2.203, P<0.05), with larger total burn area and full-thickness burn area (Z=-5.200, -6.297, P<0.01), worse acute physical and chronic health evaluation (APACHE) Ⅱ score, abbreviated burn severity index score, and sequential organ failure assessment (SOFA) score on admission (Z=-7.485, -4.739, -4.590, P<0.01), higher occurrence rate of sepsis (χ(2)=33.087, P<0.01), higher rates of accepting tracheotomy, mechanical ventilation, and continuous renal replacement therapy (χ(2)=12.373, 17.201, 43.763, P<0.01), larger first excision area (Z=-2.191, P<0.05), and higher mortality on post injury days 30, 60, and 90 (χ(2)=7.483, 37.259, 45.533, P<0.01). There were no statistically significant differences in sex, open decompression, admission time, 24-hour fluid volume after admission, 48-hour fluid volume after admission, the first 24-hour urine volume, the second 24 hour urine volume, the first excision time, and inhalation injury (χ(2)=0.529, 3.318, Z=-1.746, -0.016, -1.199, -1.824, -0.625, -1.747, P>0.05). The rates of deep vein catheterization of patients in the two groups were both 100%. (2) There were twenty possible prediction variables for preliminary establishment of model according to the difference results of single factor analysis and clinical significance of variables. (3) The logistic regression prediction model had three variables: APACHE Ⅱ score [odds ratio (OR)=1.36, 95% confidence interval (CI)=1.20-1.53, P<0.001], sepsis (OR=2.63, 95% CI=0.90-7.66, P>0.05), and the first 24-hour urine volume (OR=0.71, 95% CI=0.50-1.01, P>0.05). The AUC of the logistic regression prediction model was 0.875 (95% CI=0.821-0.930), with the specificity and sensitivity of optimal threshold value 84.4% and 77.7%, respectively. (4) XGBoost machine learning model had seven main predictive variables: APACHE Ⅱ score, full-thickness burn area, 24-hour fluid volume after admission, sepsis, the first 24-hour urine volume, SOFA score, and 48-hour fluid volume after admission. The AUC of machine learning model was 0.920 (95% CI=0.879-0.962), higher than that of logistic regression model (P<0.001), with the specificity and sensitivity of optimal threshold value 89.7% and 82.0%, respectively. Conclusions: Sepsis and fluid resuscitation are two important predictive variables that can be intervened for AKI in severely burned patients. Machine learning method has a better performance and can provide more accurate prediction for individuals than logistic regression prediction model, and therefore has good clinical application prospect.

Epidemiology and outcomes of bloodstream infections in 177 severe burn patients from an industrial disaster: a multicentre retrospective study.

OBJECTIVES: To determine the characteristics of bloodstream infections (BSIs) and to evaluate the impact of BSIs on mortality in severe burn patients. METHODS: A retrospective observational study was conducted in 20 tertiary hospitals. A total of 185 patients who experienced a massive dust explosion in eastern China were included. RESULTS: After exclusion, 177 patients were analysed. The median total body surface area (TBSA) burned was 95% (interquartile range 85%-98%). Inhalation injuries occurred in 97.2%. The overall 90-day mortality was 35% (62/177). During the study period, 120 (67.8%) patients developed 253 episodes of BSI with 323 unique causative pathogens. Sixty-six episodes were polymicrobial infections. Catheter-related BSIs (CRBSIs) accounted for 41.5% of the episodes. Acinetobacter baumannii (19.5%), Klebsiella pneumoniae (13.9%) and Candida (12.7%) were the most common organisms. Antimicrobial resistance was found in 63.5% of the isolates, particularly in Gram-negative bacteria. Patients who developed BSIs had a greater illness severity at admission to the intensive care unit, and worse outcomes. After adjusting for demographics, severity of illness and treatment characteristics in a multivariate logistic model, there was a trend toward BSI increasing the risk of 90-day mortality (adjusted OR 3.4; 95% CI 0.9-12.9; p=0.069). In subgroup analyses, CRBSIs (adjusted OR 5.7; 95% CI 1.3-24.9; p=0.021 versus no BSI) and polymicrobial BSIs (adjusted OR 6.1; 95% CI 1.3-28.1; p=0.020 versus no BSI) had greater risk of 90-day mortality. CONCLUSIONS: A strikingly high rate of BSIs was observed in severe burn patients. Gram-negative organisms and fungi were the leading causes. CRBSIs and polymicrobial BSIs were associated with high mortality.

[Effects of caspase-1 inhibitor VX765 on cold-restraint stress-induced acute gastric ulcer in mice].

Objective: To investigate the protective effects of caspase-1 inhibitor VX765 on gastric mucosa of mice with cold-restraint stress-induced acute gastric ulcer. Methods: Twenty-four specific pathogen free male C57BL/6J mice were divided into normal control group (NC), cold restrain group (CR), VX765 pre-treatment+ cold restrain group (VCR), and rabeprazole pre-treatment+ cold restrain group (RCR) according to the random number table, with 6 mice in each group. Mice in group NC were injected intraperitoneally with solution of 10 mL/kg dimethylsulfoxide (DMSO) and phosphate buffer solution (PBS). Mice in group CR were inflicted with acute gastric ulcer induced by cold-restraint stress 30 minutes after intraperitoneal injection of solution of DMSO and PBS. Mice in groups VCR and RCR were inflicted with acute gastric ulcer as above 30 minutes after intraperitoneal injection of solution of DMSO and PBS with dose of 12.5 µmol/kg containing 10 mg VX765 and 40 mg/kg containing 20 mg rabeprazole, respectively. Four hour after cold-restraint stress, serum content of tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6)was determined by enzyme-linked immunosorbent assay. Gross condition of gastric tissue was observed. Ulcer index was evaluated. Pathological change of gastric tissue was observed with HE staining. The relative expression of IL-1ß, IL-18, and cleaved-caspase-1 in gastric tissue were detected by Western blotting. Mice in group NC were detected as above at the same time point. Data were processed with one-way analysis of variance and Bonferroni test. Results: The serum content of TNF-α and IL-6 and the relative expression of cleaved-caspase-1, IL-1ß, and IL-18 in gastric tissue of mice in group NC were significantly lower than those in group CR (with P values below 0.01). The content of the above-mentioned inflammatory indexes in serum and gastric tissue of mice in group VCR was significantly lower than that in group CR (with P values below 0.01). There were no statistically significant differences in content of the above-mentioned inflammatory indexes in serum and gastric tissue of mice between groups RCR and CR (with P values above 0.05). The content of the above-mentioned inflammatory indexes in serum and gastric tissue of mice in group VCR was significantly lower than that in group RCR (with P values below 0.01). Surface of gastric mucosa was smooth and morphology of mucosal cells was normal with clear structure of mice in group NC. Multiple hemorrhage of gastric mucosa, disorderly arrangement of mucosal cells, and large number of inflammatory cell infiltration around necrotic tissue were observed in mice of group CR. Decreased number of gastric mucosa bleeding, intact mucosal structure, and small amount of inflammatory cell infiltration around necrotic tissue were observed in mice of groups VCR and RCR. The ulcer indexes of mice in groups NC, CR, VCR, and RCR were 0, 18.7±1.1, 6.3±1.5, and 8.2±1.3, respectively. The ulcer index of mice in group NC was significantly lower than that in the other 3 groups (with P values below 0.05). The ulcer indexes of mice in groups VCR and RCR were close (P>0.05), which were significantly lower than ulcer index of mice in group CR (with P values below 0.05). Conclusions: VX765 can effectively inhibit the activation of caspase-1, reduce production of inflammatory factor, and alleviate inflammatory response, which have protective effects on gastric mucosa of mice with cold-restraint stress-induced acute gastric ulcer.

[Advances in preparation and clinical application of amniotic membrane graft].

Amniotic membrane has been used as wound dressing for more than 100 years. With the development of the preservation and preparation techniques, amniotic membrane is widely used in ophthalmology, burns, plastic surgery, dentistry, and neurosurgery. In recent years, as more and more amniotic membrane is used in chronic wounds, it will be a new treatment method for wounds. This paper is a brief review about advances in preparation and clinical application of amniotic membrane graft.

[Empirical therapy of bloodstream infections caused by extended-spectrum ß-lactamase-producing Enterobacteriaceae].

OBJECTIVE: To compare the clinical outcomes and costs associated with carbapenems and ß-lactam/ß-lactamase inhibitor combinations (BLBLIs) for the empirical treatment of patients with extended-spectrum ß-lactamase (ESBL)-positive Enterobacteriaceae bloodstream infections (BSIs). METHODS: The medical records of individuals diagnosed with ESBL-producing Escherichia coli and Klebsiella pneumoniae BSIs between January 2014 and June 2015 at Changhai Hospital were reviewed. Patients were divided into two groups based on the empirical therapy (carbapenems group and BLBLIs group). Propensity score matching in a 1∶1 ratio was used to match the patients from two groups. Clinical outcomes and costs were compared before and after matching. RESULTS: One hundred and fifty-eight patients were analyzed, 93 in the carbapenems group and 65 in the BLBLIs group. Before matching, the two groups were significantly different in department distribution, tumor rate, deep vein catheter rate, urinary catheter rate, nasogastric tube rate, and mechanical ventilation rate (all P<0.05), and the carbapenems group had longer total length of stay (LOS) and post-BSI LOS (26.0 vs 18.0 d, P=0.029 and 12.0 vs 10.0 d, P=0.044) , higher hospital cost and daily hospital cost (84 120 vs 39 000 ï¿¥, P<0.001 and 3 451 vs 2 574 ï¿¥, P=0.002). After matching, the two groups had no significant differences in covariates such as sex, age, department distribution, pathogens, comorbidities, invasive interventions, LOS before BSI, multiple admissions, surgical rate during hospitalization and delayed antimicrobial therapy (all P>0.05). Finally, there were no differences between two groups in mortality, post-BSI LOS, total LOS, hospital cost and antimicrobial cost (all P>0.05). CONCLUSION: BLBLIs may provide a reasonable carbapenem-sparing option for the empirical treatment of ESBL producers.

[Impact of extended-spectrum ß-lactamase on clinical outcome and medical cost in patients with bloodstream infection due to Klebsiella pneumoniae].

OBJECTIVE: To evaluate the impact of extended-spectrum ß-lactamase (ESBL) on clinical outcome and medical cost in patients with bloodstream infection (BSI) due to Klebsiella pneumoniae. METHODS: A retrospective study was conducted in patients admitted into Changhai Hospital between January 2013 and December 2014, who suffered from BSI due to Klebsiella pneumoniae during hospitalization. Patients were divided into two groups according to whether Klebsiella pneumoniae produced ESBL (ESBL positive group and ESBL negative group). They were matched with propensity score matching method in a 1∶1 ratio and then multiple regression model was used to analyze the impact of ESBL on clinical outcome and medical cost. Clinical outcome was evaluated by 30-day mortality post BSI; medical cost was evaluated by total length of stay (LOS), post-BSI LOS, total hospital cost and antimicrobial cost. RESULTS: Before matching, the two groups were significantly different in age, nosocomial infection rate, LOS before BSI and surgical rate during hospitalization (all P<0.05). The ESBL-positive group had higher 30-day mortality post BSI (21.3% vs 8.7%, P=0.054), and higher total LOS [25.0(12.0, 33.0) vs 16.0(10.0, 23.0) d, P=0.015], post-BSI LOS [16.0(9.0, 26.0) vs 10.0(5.0, 16.0) d, P=0.006], total hospital cost [69 409(40 605, 198 021) vs 45 683(28 448, 67 000) ï¿¥, P<0.001] and antimicrobial cost [10 279(4 815, 25 500) vs 3 783(1 596, 11 879) ï¿¥, P<0.001]. After matching, the two groups had no significant differences in clinical characteristics such as sex, age, nosocomial infection rate, LOS before BSI, APACHEⅡ score, Charlson Comorbidity Index, underlying diseases and surgical rate during hospitalization (all P>0.05). Multiple regression analysis indicated that ESBL could significantly increase the total LOS, post-BSI LOS, total hospital cost and antimicrobial cost (all P<0.001), but did not increase the 30-day mortality post BSI (P=0.910). CONCLUSIONS: ESBL can significantly increase the medical cost in patients with BSI due to Klebsiella pneumoniae but does not increase the 30-day mortality post BSI.

A new strategy of using keratinocytes for skin graft: animal experimental study of keratinocyte suspension combined with the dermal substitutes.

OBJECTIVE: To provide a new and simple strategy for keratinocyte transplantation. METHODS: Keratinocyte suspension and dermal substitutes including acellular dermal matrix (ADM) and collagen membrane were prepared. Full-thickness skin defect wounds of Balb/c-nu mice were created and the mice were assigned into 5 groups: the control group, where the wound was grafted with keratinocyte suspension only; the one-step ADM and collagen membrane groups, where the wound was grafted with ADM or collagen membrane plus dripping of keratinocyte suspension; the two-step ADM and collagen membrane groups, where keratinocyte suspension was dripped 2 weeks after ADM or collagen membrane grafting. The percentage of epithelium was observed. RESULTS: Two weeks after grafting, no evidence of re-epithelialization was seen in the one-step ADM group, and the re-epithelialization rate in the one-step collagen membrane group, two-step ADM group and two-step collagen membrane group was 54.1, 41.8 and 76.8%, respectively, indicating that the re-epithelialization rate in the two-step collagen membrane group was higher than that in the other two groups (p < 0.01). CONCLUSIONS: Keratinocyte suspension combined with dermal substitutes grafting offers a more flexible way of making use of keratinocytes. Compared with ADM, microporous collagen membrane is a more preferable option for combined use with keratinocyte suspension for skin grafting.

The role of pores in acellular dermal matrix substitute.

To promote the engraftment rate of autologous skin combined with acellular dermal matrix (ADM), ADM was punched to produce regular pores from 500 to 800 µm in diameter, separated by a distance of 3 to 5 mm. The porous ADM was then implanted beneath the flap and transplanted onto an open full-thickness defect wound combined with autografts about 0.2 mm thick in a rat model. The change in diameter of pores in ADM and the neovascularization of ADM matrix were evaluated, and the take rate of porous ADM combined with overlying autologous skin was compared with that of non-porous ADM. The results showed that when porous ADM was grafted onto the full-thickness skin excised wound, plasma penetrated from the wound bed to the surface of ADM through these pores, i.e. the pores punched on ADM were responsible for the imbibition function. Subdermal implantation of ADM indicated that one week post-operation the pores in ADM were still detectable, and some of them contained red blood cells. Two to three weeks after grafting the pores became smaller, partly because of newly synthesized collagen matrix deposition. In Sprague-Dawley rats the engraftment rate of autologous sheet skin graft placed over ADM with pores was 89.5%, which was significantly higher than ADM without pores (63.2%). It is concluded that porous ADM could serve as a good dermal substitute.

Transplantation of Composite Skin Containing Keratinocytes Cultured on a Fibroblast-conditioned Acellular Dermal Matrix.

To evaluate the role of fibroblasts in composite skin reconstructed in vitro, four different types of composite skin (A, B, C, and D) were prepared. Human keratinocytes were seeded onto the epidermal side of an acellular dermal matrix (ADM) in type A. Keratinocytes were seeded onto the epidermal side of an ADM and human fibroblasts onto the dermal side in type B. Both keratinocytes and fibroblasts were seeded onto the epidermal side in type C. Type D consisted of fibroblasts on both sides of the ADM and keratinocytes on the epidermal side. The adherence of keratinocytes to the ADM was observed. The composite skin was then transplanted onto full-thickness skin defect wounds in nude mice. Results showed that the adherence of keratinocytes to the ADM was improved when fibroblasts were pre-seeded onto the epidermal side of the ADM. The composite skin was able to close full-thickness skin defect wounds. The take rates were respectively 44.1 ± 7.8%, 47.3 ± 5.4%, 75.2 ± 8.8%, and 81.2 ± 8.1% for types A, B, C, and D. The take rates of types C and D were significantly higher than those of types A and D. There was no significant difference in take rate between types C and D. In conclusion, composite skin consisting of keratinocytes cultured on a fibroblast-conditioned ADM was a good skin substitute.