ABSTRACT
Objective To preliminarily optimize the energy and density of laser radiation for the early treatment of hyperplastic scars in a rabbit ear model,and to explore possible therapeutic mechanisms.Methods Sixty-one hyperplastic scars were successfully established on the ears of 10 healthy New Zealand white rabbits with large ears,and randomly divided into 2 groups:1-week group (30 scars) and 3-week group (31 scars).These 2 groups were separately divided into 5 subgroups:group A treated with laser at a density of 100 PPA and an energy of 10 mJ,group B with laser at a density of 100 PPA and an energy of 50 mJ,group C with laser at a density of 169 PPA and an energy of 10 mJ,group D with laser at a density of 169 PPA and an energy of 50 mJ,and group E receiving no treatment.There were 6 scars in each group,except the group E in the 3-week group.Two healthy New Zealand white rabbits with large ears were not subjected to modeling,and served as group F (blank control group).Immunohistochemical study was performed to determine the expression of matrix metalloproteinase (MMP)-13 in the skin tissues from the rabbit ears 1 week after the treatment.Three weeks after the treatment,the skin tissues from the rabbit ears were subjected to hematoxylin-eosin (HE) staining and Masson staining.Then,the structure of scars was observed,and scar elevation index was calculated.Statistical analysis was carried out by Kruskal-Wallis H test for the comparison of scar elevation index,and by one-way analysis of variance (ANOVA) for the comparison of the average absorbance value of MMP-13.Results As HE staining revealed,the groups A,B,C and D all showed thicker dermis and increased number of collagen fibers compared with the group F (normal skin tissues),but showed thinner dermis,decreased number and more ordered arrangement of collagen fibers compared with the group E (untreated scar tissues).No obvious difference was observed in the thickness of the dermis among the groups A,B,C and D.The scar elevation index significantly differed among the 6 groups (H =22.757,P ＜ 0.05).Multiple comparisons showed that the scar elevation index was significantly lower in the groups B,C and D (2.597 ± 0.344,2.850 ± 0.282,2.658 ± 0.134,respectively)than in the group E (3.460 ± 0.583,all P ＜ 0.05).As Masson staining revealed,the groups A,B,C and D all showed thinner dermis and more irregular arrangement of collagen fibers compared with the group E.However,no obvious differences were observed in the dermal thickness or number of collagen fibers among the groups A,B,C and D.Immunohistochemical study showed that the expression of MMP-13 was significantly higher in the high-energy (50 mJ) laser groups than in the low-energy (10 mJ) laser groups (P ＜ 0.05) at the same laser density.With the same laser energy,the expression of MMP-13 was significantly higher in the group A than in the group C (P ＜ 0.01),but there was no significant difference between the group B and D (P ＞ 0.05).Conclusions Non-ablative fractional laser is effective for the treatment of early-stage hyperplastic scars.At the same laser density,50-mJ laser was superior to 10-mJ laser for the treatment of hyperplastic scars,likely because high-energy laser can stimulate the recombination of extracellular matrices and up-regulated MMP-13 expression to a greater extent.
ABSTRACT
Objective This paper explored the effect of the early clinical exposure in im-proving medical students' cognitive aspects of the doctor-patient relationship. Methods (1)From 280 undergraduate students of Grade 2010 who participated in early clinical exposure of Xi'an Jiaotong University College of Medicine and 280 undergraduate students of Grade 2011 who did not participate in the early clinical exposure, we selected 140 students respectively to conduct a simple random sam-pling survey. The results were analyzed by SPSS after using Microsoft Excellsoftware for entry. Statis-tical methods selected χ2-test/Fisher exact test(P<0.05). (2)We had an interview to students,teachers leading the project, instructor,experts engaging in the study of the doctor-patient relationship by using focus group discussion and in-depth interview, and then using thematic analysis to analyze the data. (3)The main aspects of questionnaires and interviews were: details, activity participation/interest, general cognitive on the doctor-patient relationship, passion for profession, choice of career, the effect in improving medical students' cognitive aspects of the doctor-patient relationship and the suggestions and comments. Results The effective questionnaires collected from Grade 2010 were 134, and124 from Grade 2011.The participation rate of the undergraduates of Grade 2010(participating group) was 94.0%(126/134), while the interest rate of undergraduates of Grade 2011 (control group) was only 76.6%(95/124). Participating group had a better cognitive understanding of doctor-patient relationship than control group(P=0.0192). The activities had significant effects on choice of career(P=0.0002), and no effect on passion for profession(P=0.7372). There was statistically significant difference on their views of employment(P=0.0002). The key words for the interview were: not enough preparation before activity, not reasonable timing, teachers leading the project, stimulation of professional pride. Conclusions Early clinical exposure activities can be effective in improving medical students' awareness of the current doctor-patient relationship. Still we have some shortages in the activity, some more exploration and amelioration should be made in late stage.