Objective To investigate the feasibility of magnetic tracer technique for locating pulmonary nodules.Methods A tracer magnet and a matching puncture instrument were designed by ourselves for locating pulmonary nodules.After preliminarily verifying the feasibility of the operation in the isolated lung,four beagle dogs were used as animal models to perform puncture localization of the assumed lesions in the upper lobe of the right lung under the guidance of X-ray by using self-designed tracer magnets and puncture instruments,and the positioning effect was observed and evaluated after thorax opening.The operation time required for the tracer magnet implantation,whether there is bleeding at the puncture site,whether the tracer magnet is displaced,and the positioning time of pulmonary nodules after thorax opening were recorded.Results Two tracer magnets were successfully inserted into the upper lobe of the right lung under X-ray guidance in four beagle dogs,and the magnets were successfully attracted and fixed.The median insertion time of the tracer magnet was 5 minutes(4 to 7 minutes),and the insertion process was smooth without bleeding at the puncture site.After thorax opening,oval forceps were used to conveniently locate the location of the tracer magnet,achieving accurate positioning of pulmonary nodules with a median positioning time of 13 seconds(10 to 17 seconds),and the tracer magnet did not shift during the whole process.Conclusion The magnetic tracer technique is simple to operate and pricise for localization of pulmonary nodules.With further optimization of the operation process,this technique is expected to be applied in clinic.

Objective:To evaluate the role of docosahexaenoic acid (DHA) in long-term cognitive impairment after multiple sevoflurane anesthesia in newborn mice.Methods:Clean-grade healthy male C57BL/6 mice, aged 6 days, were used in this study. Ten mice were divided into 2 groups ( n=5 each) by the random number table method: control group (group C) and sevoflurane group (group S). The animals inhaled 3% sevoflurane for 2 h at 6, 7 and 8 days after birth. The DHA content was detected by ultra-high performance liquid chromatography-mass spectrometry at 9 days of age. Fifty-two mice were selected and divided into 4 groups ( n=13 each) by a random number table method: control+ normal saline group (group C+ S), sevoflurane anesthesia + normal saline group (group S+ S), control+ DHA group (group C+ D), and sevoflurane anesthesia+ DHA group (group S+ D). The sevoflurane anesthesia method was the same as the one mentioned above. DHA 50 mg/kg was administered by intragastric gavage from postnatal days 6-19 (at 6, 7 and 8 days after birth, 2 h before anesthesia) in C+ D and S+ D groups. The equal volume of normal saline was given instead in C+ S group and S+ S group. The novel object recognition test was conducted at 37 days of age, and the Morris water maze test was performed at 42 days of age. The corpus callosum and hippocampal tissues were isolated at 47 days of age for examination of the ultrastructure of myelin (with a transmission electron microscope) and for determination of the expression of myelin basic protein (MBP) in hippocampal tissues (by Western blot). The G-ratio was calculated. Results:Compared with group C, the content of DHA in hippocampal tissues was significantly decreased in group S ( P<0.05). Compared with group C+ S, the discrimination index was significantly decreased, the percentage of duration of staying at the target platform quadrant and the number of crossing the original platform were decreased, the expression of MBP was down-regulated, and the G-ratio in the original platform and hippocampus was increased in S+ S group ( P<0.05). Compared with group S+ S, the discrimination index was significantly increased, the percentage of duration of staying at the target platform quadrant and the number of crossing the original platform were increased, the expression of MBP was up-regulated, and the G-ratio in the original platform and hippocampus was decreased in S+ D group ( P<0.05). Conclusions:The mechanism of long-term cognitive impairment following multiple sevoflurane anesthesia may be related to a decrease in the content of DHA, which subsequently leads to myelin structural damage in neonatal mice.

Objective:To evaluate the relationship between preoperative gut microbiota and post-operative ventilator-associated pneumonia (VAP) in patients undergoing coronary artery bypass grafting.Methods:This was a secondary analysis of a previous research project study. Patients who received invasive mechanical ventilation treatment after elective off-pump coronary artery bypass grafting at the Second Hospital of Hebei Medical University from April to September 2023 were selected and divided into VAP group and non-VAP group based on whether VAP occurred after surgery. Fecal samples were collected from patients before surgery, and 16S rRNA gene sequencing was used to analyze the characteristics of preoperative gut microbiota in the two groups. The differences in the diversity of gut microbiota between the two groups were compared. The linear discriminant analysis was used to identify the gut microbiota with significant differences between groups (differential bacteria), and logistic regression analysis was conducted to assess the association between differential bacteria and VAP. Receiver operating characteristic curves were drawn to analyze the predictive value of the differential bacteria for VAP.Results:A total of 79 patients were finally included, with 25 in VAP group and 54 in non-VAP group. The Beta diversity analysis showed statistically significant differences between VAP group and non-VAP group (pseudo- F=2.00, P=0.002). The linear discriminant analysis indicated that Bifidobacterium, Blautia and Megamonas were enriched in non-VAP group, while Klebsiella was enriched in VAP group. Multivariate logistic regression analysis showed that the relative abundance of Bifidobacterium was a protective factor for postoperative VAP ( OR=0.32, 95% confidence interval [ CI] 0.15-0.71, P=0.005), and the relative abundance of Klebsiella was a risk factor for postoperative VAP ( OR=2.49, 95% CI 1.143-5.43, P=0.022). The area under the receiver operating characteristic curve of the relative abundance of Bifidobacterium for predicting VAP was 0.80 (95% CI 0.69-0.90, P<0.001) and of the relative abundance of Klebsiella was 0.70 (95% CI 0.57-0.83, P=0.005). Conclusions:Bifidobacterium is a protective factor, while Klebsiella is a risk factor for postoperative VAP in patients undergoing coronary artery bypass grafting, and the relative abundance of both bacteria has a certain predictive value for VAP.

Objective To investigate the feasibility of magnetic tracer technique for locating pulmonary nodules.Methods A tracer magnet and a matching puncture instrument were designed by ourselves for locating pulmonary nodules.After preliminarily verifying the feasibility of the operation in the isolated lung,four beagle dogs were used as animal models to perform puncture localization of the assumed lesions in the upper lobe of the right lung under the guidance of X-ray by using self-designed tracer magnets and puncture instruments,and the positioning effect was observed and evaluated after thorax opening.The operation time required for the tracer magnet implantation,whether there is bleeding at the puncture site,whether the tracer magnet is displaced,and the positioning time of pulmonary nodules after thorax opening were recorded.Results Two tracer magnets were successfully inserted into the upper lobe of the right lung under X-ray guidance in four beagle dogs,and the magnets were successfully attracted and fixed.The median insertion time of the tracer magnet was 5 minutes(4 to 7 minutes),and the insertion process was smooth without bleeding at the puncture site.After thorax opening,oval forceps were used to conveniently locate the location of the tracer magnet,achieving accurate positioning of pulmonary nodules with a median positioning time of 13 seconds(10 to 17 seconds),and the tracer magnet did not shift during the whole process.Conclusion The magnetic tracer technique is simple to operate and pricise for localization of pulmonary nodules.With further optimization of the operation process,this technique is expected to be applied in clinic.

Objective:To compare the efficacy and safety of crisaborole ointment 2% versus pimecrolimus cream 1% in the treatment of mild to moderate atopic dermatitis in children aged 2 years or older.Methods:A multicenter, randomized, open-label, controlled clinical trial was conducted. A total of 120 pediatric patients aged 2 - 17 years with mild to moderate atopic dermatitis were enrolled from departments of dermatology of 8 hospitals in China between March 2022 and February 2023. The participants were randomly assigned in a 1∶1 ratio to the crisaborole group and the pimecrolimus group, and received the treatment with crisaborole ointment 2% and pimecrolimus cream 1% respectively, twice a day for 4 weeks. Visits were scheduled at baseline/on day 1, as well as on days 8, 15, and 29. The primary efficacy outcome was the percentage of patients achieving the Investigator's Static Global Assessment (ISGA) success (defined as clear [0] or almost clear [1] on the ISGA scale, combined with ≥ 2‐grade improvement from baseline) on day 29. The secondary efficacy outcomes included changes in the Eczema Area and Severity Index (EASI) total scores from baseline to day 29, percentages of patients achieving ISGA improvement (defined as clear [0] or almost clear [1] on the ISGA scale), as well as changes in the Peak Pruritus Numerical Rating Scale (NRS) scores, Dermatology Life Quality Index (DLQI) /Infants' Dermatology Life Quality Index (IDLQI) /Children's Dermatology Life Quality Index (CDLQI) scores, and in the Dermatitis Family Impact (DFI) scores. Drug safety was evaluated according to the incidence of adverse events. Categorical data were compared using the chi-square test. Since measurement data did not follow a normal distribution, the rank sum test was used for comparisons of measurement data between groups.Results:A total of 106 children with mild to moderate atopic dermatitis were included in the per-protocol analysis set, with 52 in the crisaborole group (26 males and 26 females) and 54 in the pimecrolimus group (27 males and 27 females). There were no significant differences in age, disease duration, ISGA and EASI scores at baseline between the two groups (all P > 0.05). On day 29, 22 patients (42.31%) in the crisaborole group and 25 (46.30%) in the pimecrolimus group achieved ISGA success, with no significant difference between the two groups ( χ2 = 0.17, P = 0.68) ; 35 patients (67.31%) in the crisaborole group and 45 (83.33%) in the pimecrolimus group achieved ISGA improvement, also with no significant difference between the two groups ( χ2 = 3.68, P = 0.06) ; additionally, there were no significant differences in the EASI, pruritus NRS, DLQI/IDLQI/CDLQI, or DFI scores between the two groups (all P > 0.05). Adverse reactions to the two topical agents were mainly local reactions such as mild to moderate pain, itching, or worsening of itching, and no obvious systemic adverse reactions occurred. The incidence of drug-related adverse reactions was 46.15% (24 cases) in the crisaborole group and 37.04% (20 cases) in the pimecrolimus group, with no significant difference between the two groups ( χ2 = 0.91, P = 0.34) . Conclusion:The efficacy of crisaborole ointment 2% was comparable to that of pimecrolimus cream 1% in the treatment of mild to moderate atopic dermatitis in children aged ≥ 2 years, and it yielded early and rapid improvement in the quality of life of patients and their families, with good safety and tolerability profiles.

Objective:To evaluate the role of docosahexaenoic acid (DHA) in long-term cognitive impairment after multiple sevoflurane anesthesia in newborn mice.Methods:Clean-grade healthy male C57BL/6 mice, aged 6 days, were used in this study. Ten mice were divided into 2 groups ( n=5 each) by the random number table method: control group (group C) and sevoflurane group (group S). The animals inhaled 3% sevoflurane for 2 h at 6, 7 and 8 days after birth. The DHA content was detected by ultra-high performance liquid chromatography-mass spectrometry at 9 days of age. Fifty-two mice were selected and divided into 4 groups ( n=13 each) by a random number table method: control+ normal saline group (group C+ S), sevoflurane anesthesia + normal saline group (group S+ S), control+ DHA group (group C+ D), and sevoflurane anesthesia+ DHA group (group S+ D). The sevoflurane anesthesia method was the same as the one mentioned above. DHA 50 mg/kg was administered by intragastric gavage from postnatal days 6-19 (at 6, 7 and 8 days after birth, 2 h before anesthesia) in C+ D and S+ D groups. The equal volume of normal saline was given instead in C+ S group and S+ S group. The novel object recognition test was conducted at 37 days of age, and the Morris water maze test was performed at 42 days of age. The corpus callosum and hippocampal tissues were isolated at 47 days of age for examination of the ultrastructure of myelin (with a transmission electron microscope) and for determination of the expression of myelin basic protein (MBP) in hippocampal tissues (by Western blot). The G-ratio was calculated. Results:Compared with group C, the content of DHA in hippocampal tissues was significantly decreased in group S ( P<0.05). Compared with group C+ S, the discrimination index was significantly decreased, the percentage of duration of staying at the target platform quadrant and the number of crossing the original platform were decreased, the expression of MBP was down-regulated, and the G-ratio in the original platform and hippocampus was increased in S+ S group ( P<0.05). Compared with group S+ S, the discrimination index was significantly increased, the percentage of duration of staying at the target platform quadrant and the number of crossing the original platform were increased, the expression of MBP was up-regulated, and the G-ratio in the original platform and hippocampus was decreased in S+ D group ( P<0.05). Conclusions:The mechanism of long-term cognitive impairment following multiple sevoflurane anesthesia may be related to a decrease in the content of DHA, which subsequently leads to myelin structural damage in neonatal mice.

Objective:To evaluate the relationship between preoperative gut microbiota and post-operative ventilator-associated pneumonia (VAP) in patients undergoing coronary artery bypass grafting.Methods:This was a secondary analysis of a previous research project study. Patients who received invasive mechanical ventilation treatment after elective off-pump coronary artery bypass grafting at the Second Hospital of Hebei Medical University from April to September 2023 were selected and divided into VAP group and non-VAP group based on whether VAP occurred after surgery. Fecal samples were collected from patients before surgery, and 16S rRNA gene sequencing was used to analyze the characteristics of preoperative gut microbiota in the two groups. The differences in the diversity of gut microbiota between the two groups were compared. The linear discriminant analysis was used to identify the gut microbiota with significant differences between groups (differential bacteria), and logistic regression analysis was conducted to assess the association between differential bacteria and VAP. Receiver operating characteristic curves were drawn to analyze the predictive value of the differential bacteria for VAP.Results:A total of 79 patients were finally included, with 25 in VAP group and 54 in non-VAP group. The Beta diversity analysis showed statistically significant differences between VAP group and non-VAP group (pseudo- F=2.00, P=0.002). The linear discriminant analysis indicated that Bifidobacterium, Blautia and Megamonas were enriched in non-VAP group, while Klebsiella was enriched in VAP group. Multivariate logistic regression analysis showed that the relative abundance of Bifidobacterium was a protective factor for postoperative VAP ( OR=0.32, 95% confidence interval [ CI] 0.15-0.71, P=0.005), and the relative abundance of Klebsiella was a risk factor for postoperative VAP ( OR=2.49, 95% CI 1.143-5.43, P=0.022). The area under the receiver operating characteristic curve of the relative abundance of Bifidobacterium for predicting VAP was 0.80 (95% CI 0.69-0.90, P<0.001) and of the relative abundance of Klebsiella was 0.70 (95% CI 0.57-0.83, P=0.005). Conclusions:Bifidobacterium is a protective factor, while Klebsiella is a risk factor for postoperative VAP in patients undergoing coronary artery bypass grafting, and the relative abundance of both bacteria has a certain predictive value for VAP.

Objective:To compare the efficacy and safety of crisaborole ointment 2% versus pimecrolimus cream 1% in the treatment of mild to moderate atopic dermatitis in children aged 2 years or older.Methods:A multicenter, randomized, open-label, controlled clinical trial was conducted. A total of 120 pediatric patients aged 2 - 17 years with mild to moderate atopic dermatitis were enrolled from departments of dermatology of 8 hospitals in China between March 2022 and February 2023. The participants were randomly assigned in a 1∶1 ratio to the crisaborole group and the pimecrolimus group, and received the treatment with crisaborole ointment 2% and pimecrolimus cream 1% respectively, twice a day for 4 weeks. Visits were scheduled at baseline/on day 1, as well as on days 8, 15, and 29. The primary efficacy outcome was the percentage of patients achieving the Investigator's Static Global Assessment (ISGA) success (defined as clear [0] or almost clear [1] on the ISGA scale, combined with ≥ 2‐grade improvement from baseline) on day 29. The secondary efficacy outcomes included changes in the Eczema Area and Severity Index (EASI) total scores from baseline to day 29, percentages of patients achieving ISGA improvement (defined as clear [0] or almost clear [1] on the ISGA scale), as well as changes in the Peak Pruritus Numerical Rating Scale (NRS) scores, Dermatology Life Quality Index (DLQI) /Infants' Dermatology Life Quality Index (IDLQI) /Children's Dermatology Life Quality Index (CDLQI) scores, and in the Dermatitis Family Impact (DFI) scores. Drug safety was evaluated according to the incidence of adverse events. Categorical data were compared using the chi-square test. Since measurement data did not follow a normal distribution, the rank sum test was used for comparisons of measurement data between groups.Results:A total of 106 children with mild to moderate atopic dermatitis were included in the per-protocol analysis set, with 52 in the crisaborole group (26 males and 26 females) and 54 in the pimecrolimus group (27 males and 27 females). There were no significant differences in age, disease duration, ISGA and EASI scores at baseline between the two groups (all P > 0.05). On day 29, 22 patients (42.31%) in the crisaborole group and 25 (46.30%) in the pimecrolimus group achieved ISGA success, with no significant difference between the two groups ( χ2 = 0.17, P = 0.68) ; 35 patients (67.31%) in the crisaborole group and 45 (83.33%) in the pimecrolimus group achieved ISGA improvement, also with no significant difference between the two groups ( χ2 = 3.68, P = 0.06) ; additionally, there were no significant differences in the EASI, pruritus NRS, DLQI/IDLQI/CDLQI, or DFI scores between the two groups (all P > 0.05). Adverse reactions to the two topical agents were mainly local reactions such as mild to moderate pain, itching, or worsening of itching, and no obvious systemic adverse reactions occurred. The incidence of drug-related adverse reactions was 46.15% (24 cases) in the crisaborole group and 37.04% (20 cases) in the pimecrolimus group, with no significant difference between the two groups ( χ2 = 0.91, P = 0.34) . Conclusion:The efficacy of crisaborole ointment 2% was comparable to that of pimecrolimus cream 1% in the treatment of mild to moderate atopic dermatitis in children aged ≥ 2 years, and it yielded early and rapid improvement in the quality of life of patients and their families, with good safety and tolerability profiles.

The genomic island(GI)characteristics and virulence factor differences of clinical isolates of Burkholderia pseudomallei in Hainan Province,China were analyzed to provide a scientific basis for diagnosis and treatment of melioidosis.In total,52 B.pseudomallei isolates were collected for detection of virulence-related GIs by PCR.The whole genome sequence annotation format file was submitted on Islandviwer 4 platform,and the genomes of the same species and close relatives were added for comparison.Two algorithms,SIGI-HMM and IslandPath-DIMOB,were integrated to predict GIs and sequence a-lignments were conducted to identify specific GIs and differences in virulence factors.The genomes of 52 clinical strains could be divided into three branches based on evolutionary distance,with 82.69％(43/52)of strains concentrated in branch 1.In to-tal,828 GIs were identified among the 52 B.pseudomallei genomes,which formed 157 GI clusters based on sequence similari-ty.GIs accounted for 2.05％-6.38％of the genome content.While GI clusters 1 and 2 were present in all strains,a total of 84(53.50％)GI clusters only clustered within a single genome isolate.Of 10 GI likely specific clusters,five were from the same genus,two from another genus,and three with uncertain origins.Moreover,25 GI clusters were associated with virulence,which included eight shared by B.pseudomallei BP76 and BP169,which had the highest number of virulence-associated GIs among all isolates.O the 52 B.pseudomallei isolates,variations were identified in the virulence genes fhaB1,fhaB2,BPSL1661,cheY1,wzM,tssH-5/clpV,tssA-5,boaA,and boaB.Comparisons of these findings with clinical isolates from Thailand and Australia showed that B.pseudomallei isolates from Hainan had significant differences in the sequences of boaA,boaB,cheY1,and chbp.Additionally,fhaB1,fhaB3,and bimA displayed significant variations specifically within the Australian isolates.B.pseudomallei GI was conserved and specific to Hainan.The identification of specific GI and virulence factors was useful to clarify the source of horizontal gene transfer and differences in virulence at the molecular level.

Objective: To investigate the effects of methacrylic anhydride gelatin (GelMA) hydrogel loaded with silver and recombinant human basic fibroblast growth factor (rh-bFGF) on deep partial-thickness burn wounds in rabbits. Methods: The experimental research method was adopted. Low-concentration GelMA materials, medium-concentration GelMA materials and high-concentration GelMA materials containing different concentrations of methacrylic anhydride (MA) were prepared, after adding photoinitiator, low-concentration GelMA hydrogels, medium-concentration GelMA hydrogels, and high-concentration GelMA hydrogels were obtained, respectively. The nuclear magnetic resonance spectroscopy was performed to detect the hydrogen nuclear magnetic resonance spectra of the above-mentioned three concentrations of GelMA materials, and to calculate the degree of substitution according to the spectrum diagram. The three-dimensional microstructure and pore size of 3 types of above-mentioned GelMA hydrogels were detected by field emission scanning electron microscopy (FESEM), with 9 samples measured. According to the selected concentration of MA, ten kinds of solutions of GelMA with different concentration of silver (silver-containing GelMA) were synthesized, and the silver-containing GelMA solution of each concentration was divided into three parts, and then exposed to ultraviolet light lasting for 20, 25, and 35 s, respectively. After adding photoinitiator,the corresponding silver-containing GelMA hydrogels were obtained. The residual degradation rate of silver-containing GelMA hydrogel with different photocrosslinking times was detected by collagenase degradation method at degradation of 12, 24, 36, and 48 h; and the time required for complete degradation was detected, and the sample number was 5. The inhibition zone diameter of GelMA hydrogel under above screened photocrosslinking times containing 10 concentrations of silver against Staphylococcus aureus was measured to reflect its antibacterial ability, and the sample numbers were all 5. The silver-containing GelMA hydrogel with statistical significance compared with the antibacterial circle diameter of the silver-containing GelMA hydrogel containing the lowest concentration (no silver) was considered as having antibacterial activity. The three-dimensional microstructure and pore size of the silver-containing GelMA hydrogels with antibacterial activity and the lowest drug concentration selected were detected by FESEM, and the sample numbers were all 9. The freeze-dried alone GelMA hydrogel and the freeze-dried silver-containing GelMA hydrogel were soaked in phosphate buffer solution for 24 h, respectively, then the swelling rate of the two GelMA hydrogel were calculated and compared by weighing method, and the sample number was 5. GelMA hydrogel containing silver and rh-bFGF, namely compound hydrogel for short, was prepared according to the preliminary experiment and the above experimental results. The appearance of the composite hydrogel was observed in general, and its three-dimensional microstructure and pore size were detected by FESEM. The deep partial-thickness burn wound was made on the back of 30 rabbits (aged 4-6 months, female half and half). Meanwhile, with the rabbit head as the benchmark, the wounds on the left side of the spine were treated as composite hydrogel treatment group, and the wounds on the right side were treated as gauze control group, and which were treated accordingly. On post injury day (PID) 3, 7, 14, 21, and 28, the healing of wounds in the two groups was observed. On PID 7, 14, 21, and 28, the wound healing area was recorded and the healing rate was calculated, with a sample number of 30. Data were statistically analyzed with analysis of variance for repeated measurement, one-way analysis of variance, and independent sample t test. Results: The substitution degree among low-concentration GelMA materials, medium-concentration GelMA materials, and high-concentration GelMA materials was significantly different (F=1 628.00, P<0.01). The low-concentration GelMA hydrogel had a loose and irregular three-dimensional spatial network structure with a pore size of (60±17) μm; the medium-concentration GelMA hydrogel had a relatively uniform three-dimensional spatial network and pore size with a pore size of (45±13) μm; the high-concentration GelMA hydrogel had the dense and disordered three-dimensional spatial network with a pore size of (25±15) μm, the pore sizes of 3 types of GelMA hydrogels were significantly differences (F=12.20, P<0.01), and medium concentration of MA was selected for the concentration of subsequent materials. The degradability of silver-containing GelMA hydrogels with different concentrations of the same photocrosslinking time was basically same. The degradation residual rates of silver-containing GelMA hydrogels with 20, 25, and 35 s crosslinking time at 12 h were (74.2±1.7)%, (85.3±0.9)%, and (93.2±1.2)%, respectively; the residual rates of degradation at 24 h were (58.3±2.1)%, (65.2±1.8)%, and (81.4±2.6)%, respectively; the residual rates of degradation at 36 h were (22.4±1.9)%, (45.2±1.7)%, and (68.1±1.4)%, respectively; the residual rates of degradation at 48 h were (8.2±1.7)%, (32.4±1.3)%, and (54.3±2.2)%, respectively, and 20, 25, and 30 s photocrosslinking time required for complete degradation of silver-containing GelMA hydrogels were (50.2±2.4), (62.4±1.4), and (72.2±3.2) h, and the difference was statistically significant (F=182.40, P<0.01), 25 s were selected as the subsequent photocrosslinking time. The antibacterial diameters of 10 types of silver-containing GelMA hydrogels against Staphylococcus aureus from low to high concentrations were (2.6±0.4), (2.5±0.4), (3.2±0.4), (12.1±0.7), (14.8±0.7), (15.1±0.5), (16.2±0.6), (16.7±0.5), (16.7±0.4), and (16.7±0.6) mm, respectively, and which basically showed a concentration-dependent increasing trend, and the overall difference was statistically significant (F=428.70, P<0.01). Compared with the silver-containing GelMA hydrogel with the lowest concentration, the antibacterial circle diameters of other silver-containing GelMA hydrogels with antibacterial ability from low to high concentration were significantly increased (with t values of 26.35, 33.84, 43.65, 42.17, 49.24, 55.74, and 43.72, respectively, P<0.01). The silver-containing GelMA hydrogel with the antibacterial diameter of (12.1±0.7) mm had the lowest antibacterial activity against Staphylococcus aureus and the lowest drug loading concentration, and the concentration of silver was selected for the concentration of subsequent materials. The microscopic morphology of the silver-containing GelMA hydrogel containing silver element with a pore size of (45±13) μm had a regular and linear strip-like structure. After soaking for 24 h, the swelling ratio of silver-containing GelMA hydrogel was similar to that of alone GelMA hydrogel. The composite hydrogel was colorless, clear and transparent, and its three-dimensional microstructure was a regular and uniform grid, with a filament network structure inside, and the pore size of (40±21) μm. On PID 3, a large amount of necrotic tissue and exudate of rabbit wound in composite hydrogel group were observed, and scattered scabs, a small amount of necrotic tissue and exudate of rabbit wound in gauze control group were observed. On PID 7, the area of rabbit wound in composite hydrogel group was significantly reduced, and adhesion of rabbit wound and gauze in gauze control group was observed. On PID 14, In composite hydrogel group, the rabbit wound surface was ruddy, and the growth of granulation tissue was observed, and in gauze control group, the rabbit wound base was pale, and the blood supply was poor. On PID 21, the rabbit wounds in composite hydrogel group healed completely, and rabbit wound in gauze control group had healing trend. On PID 28, new hair could be seen on rabbit wound surface in composite hydrogel group; oval wound of rabbit in gauze control group still remained. On PID 7, 14, 21, and 28, the wound healing areas of rabbit in composite hydrogel group were significantly larger than those in gauze control group (with t values of 2.24, 4.43, 7.67, and 7.69, respectively, P<0.05 or P<0.01). Conclusions: The medium-concentration GelMA hydrogel has good physical and chemical properties in terms of swelling and degradability. The screened silver-containing GelMA hydrogels had the lowest antibacterial activity and the lowest drug loading concentration. Composite hydrogel can significantly shorten the healing time of deep partial-thickness burn wounds in rabbits.
Anhydrides ; Animals ; Anti-Bacterial Agents ; Burns/drug therapy* ; Female ; Fibroblast Growth Factor 2 ; Gelatin/pharmacology* ; Humans ; Hydrogels/pharmacology* ; Rabbits ; Recombinant Proteins ; Staphylococcal Infections ; Staphylococcus aureus