ABSTRACT
Our study investigated the neurotoxicity of quinolinic acid(QA)to spiral ganglion cells(SGCs),observed the protective effects of N-methyl-D-aspartatc(NMDA)receptor antagonist MK-801and magnesium ions on the QA-induced injury to SGCs,and analyzed the role of QA in otitis media with effusion(OME)-induced sensorineural hearing loss(SNHL).After culture in vitro for 72 h,SGCs were exposed to different media and divided into 4 groups: the blank control group,the QA injury group,the MK-801 treatment group,and the MgCl2 protection group.The apoptosis rate of SGCs was analyzed by Annexin V and PI double staining under the fluorescence microscopy 24 h later.SGCs were cultured in vitro for 72 h and divided into four groups: the low concentration QA group,the high concentration QA group,the MK-801 group,the MgCl2 group.The transient changes of intracellular calcium concentration were observed by the laser scanning confocal microscopy.Apoptosis rate in QA injury group was higher than that in blank control group and MgCl2 protection group(both P<0.05),but there was no significant difference between MK-801 treatment group and blank control group(P>0.05).In high concentration QA group,there was an obvious increase of the intracelhilar calcium concentration in SGCs,which didn't present in low concentration QA group.In MgCl2 group,the peak values of the intracellular calcium concentration in SGCs were reduced and the duration was shortened,but the intracellular calcium concentration in SGCs had no significant change in MK-801 group.It was concluded that QA could injure SGCs by excessively activating NMDA receptors on the cell membrane,which might be the mechanism by which OME induced SNHL,while Mg2+could protect the SCGs from the neurotoxicity of QA.
ABSTRACT
The aim of the present study was to assess whether Fourier transform infrared spectrometry (FTIR)micro-spectroscopy could produce distinct spectral information on protein of old myocardial infarction(OMI)and to set them as molecular markers to diagnose atypical OMI.Paraffin-embedded heart samples were derived from victims dying of OMI.In combination with histological stain,FTIR and infrared micro-spectroscopy,the characteristics of OMI were analyzed morphologicallyand molecularly.The most relevant bands identified were the amide A,B,Ⅰ and Ⅱ,showing crucial spectral differences between apparent normal region and OMI region,including the peak position blue shift and the increased intensity of OMI,moreover relative increase in a-helix and decrease in β-sheet of protein secondary structures in OMI.Comparing to single spectral band,the I1650/I1550 ratio was increased and rationally used as a molecular marker for diagnosing OMI.These novel preliminary findings supported further exploration of FTIR molecular profiling in clinical or forensic study,and were in accordance with histopathology.
ABSTRACT
To study the relationship between changes of microbial ATP in four kinds of murine tissues and the postmortem interval (PMI),healthy SD rats were sacrificed and their muscles,livers,spleens and kidneys were sampled at different postmortem intervals. The concentration of microbial ATP was detected using bioluminescent assay and the data was statistically analyzed. The concentration of microbial ATP in muscle increased with PMI time. The peak appeared at the 7th day after death,and at the 10th day,microbial ATP in muscle tissue increased again. In internal organs,the peaks of microbial ATP were observed at the 8th day after death and the level decreased during 8-10 d. The differences in microbial ATP concentration in liver,spleen and kidney were not statisticallysignificant. During day 0 to day 9 after death,the correlation was best between PMI and microbial ATP in muscle. With PMI as the independent variable,the cubic polynomial regression equation was Y=0.02X3-0.166X2-0.666X+13.412 (R2=0.989,P＜0.01). In internal organs,the best correlation was found between PMI and microbial ATP during day 0 to day 10. With PMI as the independent variable,the cubic polynomial regression equation was Y=0.016X3-0.127X2-0.809X+13.324 (R2=0.986,P＜0.01). There existed high correlations between PMI and microbial ATP concentration in rat tissues.Since only a small amount of tissue was needed for the detection and the sample was not affected by self-decomposition,the method may extend the time range of PMI estimation.