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Objective:To explore indicators related to visceral fat index by constructing a random forest model.Methods:In this cross-sectional study, the laboratory measures and body composition analysis records of 617 hospital employees (in-service and retired) who underwent physical examination in Heilongjiang Provincial Hospital Health Management Center from March to September 2021 were selected. The subjects were divided into a training set ( n=411) and a test set ( n=206) with the ratio of 2∶1. A total of 110 predictors were included in the model. The model was constructed with the training set and was evaluated with the test set. The optimal number of nodes and decision trees were selected to evaluate the prediction performance of the optimal model. And the top 10 relatively important factors were selected for further investigation. The 617 participants were further divided in to groups according to the visceral fat index: the normal or high visceral fat index group, and the differences of the top 10 relatively important factors were further compared between the two groups. Results:The optimal number of nodes of the final random forest model was 39 and the number of decision trees was 300. The accuracy, precision, sensitivity and specificity of the model was 83.3%, 73.9%, 89.4% and 78.7%, respectively. The area under the receiver operating characteristic curve and 95% confidence interval of the model was 0.881 (0.832-0.931). The top 10 relatively important factors in the model were body mass index, gender, age, serum uric acid, red blood cell count, monocyte cell count, C-peptide, carcinoembryonic antigen, glycosylated hemoglobin and glutamyl transpeptidase. There were significant differences in the up-mentioned 10 indicators between the subjects with normal and high visceral fat index (all P<0.05). Conclusions:The random forest model built in this study has good performance in predicting visceral fat index, and visceral fat is related with changes in liver function, pancreas function and immune function.
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Objective To observe the effect of simulated microgravity on the photopic negative response (PhNR) of full-field flash ERG in adult mice.Methods In an experimental study,forty-eight adult male C57BL/6J mice (48 eyes) were randomly divided into model and control groups.Model mice were further divided into three subgroups of 8 each:tail-suspended for 15 days (subgroup A),tail-suspended for 30 days (subgroup B),and tail-suspended for 30 days followed by returning to normal position for 30 days (subgroup C).The three control subgroups were similarly fixed with a harness but kept in the normal position for corresponding periods of 15,30,and 60 days.The mice were immediately examined using ERG-PhNR,flash VEP,OCT and visually-guided behavior in vivo,and subsequently sacrificed to analyze the retinal histology in vitro.PhNR amplitude was measured from baseline to PhNR trough.N1 peak-time and N1-P1 amplitude of VEP was analyzed.The escape duration was used to quantitatively evaluate the visual function of mice.In addition,inner retinal thickness was analyzed by OCT imaging.Data were compared by the independent sample t-test.Results PhNR amplitude in the model subgroup A was obviously lower than the corresponding control subgroup,the difference was statistically significant (t=-3.196,P＜0.01).There was no significant difference in PhNR amplitude between the model subgroup B or C and the corresponding control subgroup (t=-1.976,0.285;P＞0.05).There was no significant difference in FVEP N1 peak-time or N1-P1 amplitude between any of the three model subgroups and the corresponding control subgroup (P＞0.05).There was no significant difference in OCT-measured inner retinal thickness between any of the three model subgroups and the corresponding control subgroup (t=-0.461,2.073,-0.402;P＞0.05).The three model subgroups showed almost normal retinal structure,including the retinal ganglion cell,inner pexiform layer,inner nuclear layer,outer plexiform layer,outer nuclear layer,ellipsoid zone and RPE.There was no significant difference in visually-guided escape time between any of the three model subgroups and the corresponding control subgroup (t=-0.637,-0.955,1.297;P＞0.05).Conclusion Via tail-suspension,short-term simulated microgravity can affect the PhNR of flash ERG;however,the change is reversible and does not affect visual function of mice.
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Background Different depthes or distances are prompted with many visual cues on the flat screen.Which kind of depth cues plays a major role in the accommodation of human eyes,in addition,whether this effect exists in the different distance are still below understood.Objective This study was to research the effect of the monocular space depth perception on accommodative response at different distances,and to analyze the effect of linear perspective and size-constancy perceptual depth cues on the level and amplitude of accommodative fluctation.Methods Four groups of visual targets were designed by FLASH software and placed at the front of eyes with the distance of 50 cm or 33.3 cm,representing static change from far to near and dynamic change from far to near,from near to far respectively.Twenty-six healthy volunteers aged 22-26 years were included in this study,with the spherical power of (-4.06± 1.99) D and cylindrical power of (-0.38±0.41) D under the informed consent.The accommodative response and accommodative fluctuations during monocularly watching the targets were recorded at 5 times/second by Grand Seiko WAM 5500 automatic infrared refractor.This study was approved by Ethic Committee of Wenzhou Medical University,and written informed consent was obtained from each subject before entering the study group.Results At the distance of 50 cm,the accommodative response caused by the depth perception of near was (1.52±0.46) D,the one of distance was (1.37±0.46) D,with a significant difference of 0.15 D under the combined effect of linear perspective and size-constancy (P =0.016).The accommodative response caused by the depth perception of big car was (1.43 ± 0.35) D,and the one of small car was (1.43 ± 0.36) D,without statistically significant difference under the effect of size-constancy alone (P =0.467).At the distance of 33.3 cm,the accommodative response caused by the depth perception of near was (2.40±0.53)D,and the one of distance was (2.35 ±0.51) D,without significant difference under the combined effect of linear perspective and size-constancy (P=0.379).The accommodative response caused by the depth perception of big car was (2.38±0.48)D,the one of small car was (2.39±0.52)D,without statistically significant difference under the effect of size-constancy alone (P =0.820).In addition,the total curve of accommodative microfluctuation showed apparent fluctuation periodically caused by the distance perception involving linear perspective only.Conclusions Monocular space depth perception has some impacts on the accommodative response at certain distance.Linear perspective,which is one of the depth cues of space perception,plays a major role in the accommodative response.Compared with the size-constancy,linear perspective can provide depth perception at higher level.The size-constancy has a little or contrast impact to the accommodation,because it depends on the assistance from other depth cues like linear perspective.
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Background Angle Kappa is the angle between the pupillary axis and visual axis,and it is a major consideration in corneal refractive surgery and strabismic surgery.Researches showed that age and refractive status affect angle Kappa value,and additionally,the measuring results of angle Kappa are associated with instruments.Objective This study was to investigate and weight the influences of axial length,anterior chamber depth and corneal curvature to angle Kappa.Methods A cross-sectional study was designed.Fifty health volunteers were included from Dec 2009 to Aug 2010,with the age of 18-38 years and average diopter of-1.0 D and best corrected visual acuity of 1.0.The horizontal and vertical angle Kappa was binocular measured with a testing machine designed by laboratory of School of Optometry & Ophthalmology Wenzhou Medical University.IOLMaster was employed to measure the ocular axial length,anterior chamber depth and corneal curvature radius.A multiple linear regression model was established to analyze the influences of axial length,anterior chamber depth and corneal curvature radius to angle Kappa.Results An efficacious regression equation was established as Y =15.554-0.587X1+0.724X2+ 0.232X3 with the independent variables as axial length(X1),anterior chamber depth (X2),corneal curvature (X3) and dependent variable as horizontal angle Kappa (Y) (R =0.788,R2 =0.621,P =0.000).Horizontal angle Kappa showed a negative correlation with axial length (b1 =-0.587,β1 =-1.002,P =0.000) and a positive correlation with anterior chamber depth (b2 =0.724,β32 =0.296,P =0.030).No significant correlation was found between corneal curvature radius and horizontal angle Kappa (b3 =-0.232,β3 =-0.068,P=0.338).A new regression equation was Y =14.235-0.622X1 + 0.824X2 after removed the corneal curvature variable (R =0.786,R2=0.618,P =0.000),with a negative correlation between horizontal angle Kappa and axial length (b1 =-0.622,β1 =-1.062,P＜0.05) or positive correlation between horizontal angle Kappa and the anterior chamber depth (b2 =0.824,β2 =0.337,P＜0.05).In addition,a multiple linear regression equation among 3 independent variables and dependent variable of vertical angle Kappa was Y =0.492-0.020X1 +0.038X2 +0.089X3 (R =0.436,R2 =0.191,P =0.000).However,no significant correlations were seen between vertical angle Kappa and axial length,anterior chamber depth or corneal curvature radius (all at P ＞ 0.05).Conclusions Ocular axial length and anterior chamber depth have an obvious influence to horizontal but not vertical angle Kappa.Axial length appears to have more influence to horizontal angle Kappa than anterior chamber depth.
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Objective To probe into the optometry students' acceptability of interactive teaching mode by the questionnaire survey.Methods Totally 207 optometry students including 42 five-year undergraduate students,17 seven-year program students,95 three-year postgraduate students and 53 three-year junior college students were investigated for their acceptability of interactive teaching mode by the questionnaire survey.Results The results showed that 63.3％ of the students preferred traditional teaching mode; 70％ of the students would like to accept interactive teaching mode,the others didn't accept it or hesitated to accept it.Lack of self-confidence was the major reason.Conclusions Most medical college students are willing to accept the interactive teaching mode.Interactive teaching mode should be combined with traditional teaching mode.
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OBJECTIVE: To investigate if hyperbaric oxygen ( HBO) may induce structural changes of neurons in hippocampus from infantile rats and if the changes are reversible. METHODS: All 27 healthy SD infantile rats were exposed to HBO (0.25 MPa) or hyperbaric air (HBA) for 1 to 3 courses (10 days as 1 course). The hippocampus was taken at the end of each course to observe its morphology b y light microscope and electron microscope. RESULTS: HBO exposure induced capillary dilation, nuclear membr ane winding or blurring and some mitochondria swelling with its crista blurring i n neurons. The changes occurred after 1 course exposure and became significant w ith time. Most of the changes recovered 20 days after stopping exposure. No chan ge was found after HBA exposure. CONCLUSIONS: Long-term HBO exposure can cause capillary dilati on and ultrastructural injury of neurons in hippocampus from infantile rats. The damage is not serious, but reversible.