[Application of methylene blue near-infrared fluorescence imaging for oral sentinel lymph node mapping in rats].

OBJECTIVE: To explore the concentration range and penetration depth of methylene blue near-infrared fluorescence imaging, and to clarify the role of methylene blue in oral lymphatic drainage and sentinel lymph node localization, so as to lay a foundation for the potential research and application of sentinel lymph node in oral cancer. METHODS: 10% (mass fraction) methylene blue injection was diluted into 29 different concentrations with 0.9% (mass fraction) normal saline, and the concentration range of methylene blue near-infrared fluorescence imaging was determined by near-infrared fluorescence imager. The maximum penetration depth of methylene blue near-infrared fluorescence was determined by covering pigskin with different thicknesses (1, 2, 3, 4 and 5 mm) in methylene blue solution. 0.2 mL methylene blue solution was injected into the submucosal 0.5 cm at the lateral margin of tongue on one side of the rats. The near-infrared fluorescence imager was used for continuously monitoring for 3 hours. The first near-infrared fluorescence hotspot was identified as sentinel lymph node and labeled by percutaneous observation. The rats were then sacrificed and dissected in the head and neck. Near-infrared fluorescence imaging was performed again to observe whether the fluorescent tissue was consistent with the labeled fluorescent hotspot in vitro, and the presence of lymphoid tissue was confirmed by pathological examination after resection. RESULTS: Except that no fluorescence signals were detected in the blank control groups, the fluorescence intensity of methylene blue increased first and then decreased with its solution concentration decreased. When the concentration of methylene blue was diluted to the picomole level, the fluorescence signal could still be detected. The maximum penetration depth of methylene blue fluorescence was 4 mm. Methylene blue near-infrared fluorescence could be localized in oral lymphatic drainage and sentinel lymph node. The fluorescence was sustained for more than 3 hours after methylene blue injection. Methylene blue solution concentrations of 3.34 mmol/L, 6.68 mmol/L, 13.37 mmol/L and 26.74 mmol/L were selected in the rats to map sentinel lymph node by near-infrared fluorescence. CONCLUSION: Methylene blue near-infrared fluorescence has a certain penetrating ability and can transcuta-neously map the sentinel lymph node and their associated lymphatic vessels in rats, which is expected to be further applied in the study of sentinel lymph node in oral cancer.

[Diversity analysis of luminal and mucosa-associated microbial communities in obese mice].

Objective: Gut microbiota have been reported to be able to regulate host metabolism and is closely associated to obesity. The purpose of this study was to explore the differences between the diversity of luminal and mucosa-associated microbial communities in obese mice. Methods: Colonic luminal contents and colonic mucosa were separately collected from 10 obese mice fed with high-fat diet for 12 weeks. DNA of gut microbiota was extracted and micro flora populations were analyzed by Illumina sequencing. Species annotation, diversity analysis, and species difference analysis were conducted. Results: The microbial flora from colonic contents had similar richness, evenness and overall structure to those from colonic mucosa (ACE index 250 vs. 285, Chao index 257 vs. 291, Shannon index 3.84 vs. 3.97, Simpson index 0.05 vs. 0.06, all P>0.05). However, there were differences in the microbial composition on specific levels. At the phylum level, colonic contents had higher abundance of Bacteroidetes (56.08% vs. 27.25%, P=3.21×10(-5)), while colonic mucosa had higher abundance of Firmicutes (49.09% vs. 34.27%, P=0.03) and proteobacteria (18.48% vs. 3.62%, P=0.000 9). At the genus level, butyrate-producing bacteria-Lactobacillus was more abundant in colonic content (LDA score=3.89), whereas gram-negative genus Helicobacter, Sphingomonas and Desulfovibrio were relatively abundant in colonic mucosa (LDA score=4.78, 3.59 and 4.11, respectively). Conclusion: There were differences in microbial composition at the phylum and genus levels between microbial flora from colonic contents and colonic mucosa, although they had similar richness, evenness and overall structure.

Urinary apolipoprotein M could be used as a biomarker of acute renal injury: an ischemia-reperfusion injury model of kidney in rat.

BACKGROUND: It has been well documented that apolipoprotein M (apoM) is principally expressed in hepatocytes as well as renal tubular epithelial cells. The importance of apoM in the kidney is unknown. In the present study we examined urinary any apoM after short-term ischemia-reperfusion injury (IRI) of kidney in a rat model. METHODS: The kidneys of 11 male Sprague-Dawley rats were rendered ischemic for 45 minutes followed by different intervals of reperfusion. Serum and urine apoM concentrations were determined using a dot-blot analysis with specific rabbit anti-human apoM antibodies that cross-react with rat apoM. Serum concentrations of blood urea nitrogen (BUN) and creatinine (Cr) were determined using standard clinical automated analyses. RESULTS: BUN was significantly elevated after 45 minutes of ischemia followed by 24 hours of reperfusion; serum Cr concentrations were also significantly increased at 6 and 24 hours of reperfusion. Interestingly, similar to BUN and Cr, serum apoM concentrations were significantly increased after ischemia for 45 minutes alone and after 2 hours of reperfusion. Urinary apoM concentrations were obviously increased after 2 h as well as 6 hours of reperfusion. CONCLUSION: apoM showed characteristics of an acute-phase reactive protein; its occurrence in urine may be considered to be a biomarker of acute renal injury.