Objective:To explore the necessity and feasibility of undergraduate tutorial system in clinical medical colleges.Methods:A questionnaire survey on the scientific research situation was conducted among 64 students from the long-term class and the base class of the Fourth Clinical Medical College of Capital Medical University from September 2015 to February 2018. The undergraduate tutorial system was tested in two classes for one year. After that, the questionnaire survey was conducted again to compare it with the system before implementation and analyze the trial situation of the tutorial system.Results:During the practice of the undergraduate tutorial system, it was found that most of the students wanted to participate in scientific research and were guided by tutors to improve their scientific research capabilities, but at the same time, it was also discovered that tutors were busy with their work and were unable to give insufficient guidance to the students. In terms of medical papers writing, from September 2015 to February 2018, 20 students in the long-term class participating in the tutorial system wrote 23 papers in total, and 9 students in the base class totally wrote 9 papers, with a significant difference ( P<0.05). From September 2015 to February 2018, 9 students from the base class wrote 9 papers, and from March 2018 to March 2019, there were 18 students from the base class who totally wrote 27 papers, with a significant difference ( P<0.05). Conclusion:It's feasible and necessary to implement the undergraduate tutorial system in clinical medical colleges.

Heat stress refers to a series of stress reactions such as heat balance disturbance and physiological dysfunction when the body is exposed to the thermal environment for a long time. Studies have found that heat stress can damage intestinal morphology, such as length of intestinal villi, number of goblet cells, and depth of the crypt, affecting the digestion and absorption functions. It also can increase the permeability of the intestinal barrier by damaging the tight junction of the intestinal epithelium, which in turn allows endotoxin and bacteria to enter the blood circulation from the intestinal cavity to cause a systemic inflammatory response. At the same time, heat stress can disrupt the homeostasis of intestinal microbiota, increase pathogenic bacteria, and change downstream metabolites such as short-chain fatty acids. In addition, heat stress can inhibit the occurrence of hippocampal neurons and reduce the number of neurons; decrease the density of synapses; damage important organelles of neurons; induce inflammation of the central nervous system, and then lead to cognitive dysfunction. The brain-gut axis is a two-way signal axis between the intestine and the brain. Intestinal microorganisms and the intestinal barrier can participate in central nervous system regulation, and the brain can change the intestinal homeostatic function and affect the quality of the intestinal barrier through the hypothalamic-pituitary-adrenal axis (HPA axis). The interaction plays an essential role in the body's homeostasis. Therefore, this article reviewed current understandings on the impacts of heat stress on the gut and cognitive function, aiming to provide a reference for subsequent research.

AIM:To explore the fundus vascular characteristics of healthy individuals based on deep learning techniques, with a view to discovering the range of normal values of the fundus arteries and veins, as well as the relationship between physiological factors, such as gender, age, body mass index(BMI), blood pressure, and fundus vasculature characteristics.METHODS:Fundus images of healthy people were taken from a professional fundus camera, and the subject's blood pressure and laboratory test was collected. Additionally, the fundus arteries and veins were segmented by the improved U-Net model, and the color, morphology and Haralick texture features of the vessels were extracted from computer vision technology.RESULTS:A total of 4 487 cases fundus images were taken and 326 cases with healthy and clear fundus images were screened, including 200 males and 126 females. There were differences in the morphology, color, and textural characteristics of the left and right eyes, as well as of the fundus arterioles and veins, with a mean vessel width(width)of 1.146 in the arteries and 1.430 in the veins, and an arteriovenous ratio about 4:5. Fundus artery and vein characteristics in healthy individuals of different ages(21-30, 31-40, 41-50): compared with the healthy population aged 21-30 and 31-40 years, arterial and venous inverse difference moment(idm), f12 and venous angular second moment(asm)values increased, and arterial and venous contrast(con), entropy(ent), difference entropy(den), and venous sum entropy(sen)values decreased in 41-50 years. Compared with the 21-30 years age group, arterial f12 values increased and venous con values decreased in 31-40 years(all P<0.05). Fundus vascular characteristics of healthy individuals of different sexes: compared with male, fundus arterial and venous sum average(sav), sum variance(sva)values, arterial curved values, and venous b mean, bsd, variance(var), sen, ent values increased in female, while venous area value of female decreased(all P<0.05). There were no statistically significant differences in fundus arteriosus and venous features in healthy subjects with different levels of BMI(all P>0.05). Fundus characteristics of healthy people with different degrees of blood pressure: there were statistically significant differences in fundus arteriosus area, width, and venous con, idm, dva, and den values between the normal blood pressure and high blood pressure groups(all P<0.05).CONCLUSION: The characteristics of the left and right eyes as well as the fundus arteries and veins differ in healthy individuals and correlate with physiological factors such as gender, age and blood pressure, which have the value of a potential microcirculation marker.