Objective: To explore the association of physical activity and sugar sweetened beverage consumption with psychological sub health among middle school students in Bao an District, Shenzhen, so as to provide a reference for adolescent mental health promotion. Methods: A questionnaire survey was conducted in November 2024 by a stratified cluster random sampling method to select 6 926 junior and senior middle school students from 5 middle schools in Shenzhen. The questionnaire from Youth Risk Behavior Surveillance System was used to assess the consumption of sugar sweetened beverages, and physical activity Rating Scale was used to assess the level of physical activity, and Brief Instrument on Psychological Health of Youths was used to evaluate the psychological sub health status. The Chi -square test was used to analyze the differences in the detection rates of psychological sub health among different groups of middle school students, and a multivariate Logistic regression model was established to analyze the effects of physical activity and sugar sweetened beverage consumption and their combined effects on the psychological sub health of middle school students. Results: The detection rate of psychological sub health among middle school students in Bao an District, Shenzhen was 18.93%. Multivariate Logistic regression analysis showed that, after controlling for confounding factors such as gender, school stage, family residence, family economic status, parental literacy, academic stress and number of friends, lack of physical activity or excessive sugar sweetened beverage consumption were associated with increased risks of psychological sub health among middle school students ( OR =1.36, 1.45); and the highest risk of psychological sub health was found in middle school students who were lack of physical activity and excessive sugar sweetened beverage consumption ( OR =2.59) ( P <0.01). Further analysis by school stages showed that junior high school students with sufficient physical activity and excessive intake of sugary drinks ( ROR =2.10), lack of physical activity and excessive intake of sugary drinks ( ROR =2.31) were at higher risks of psychological sub health than senior high school students( P <0.05). Conclusions Insufficient physical activity and excessive sugar sweetened beverage consumption are closely associated with an increased risk of psychological sub health among middle school students. Effective interventions should be targeted to reduce the risk of psychological sub health problems among middle school students.

Objective To investigate the changes in eosinophil counts and the activation of microglial cells in the brain tissues of mice at different stages of Angiostrongylus cantonensis infection, and to examine the role of microglia in regulating the progression of angiostrongyliasis and unravel the possible molecular mechanisms. Methods Fifty BALB/c mice were randomly divided into the control group and the 7-d, 14-d, 21-day and 25-d infection groups, of 10 mice in each group. All mice in infection groups were infected with 30 stage III A. cantonensis larvae by gavage, and animals in the control group was given an equal amount of physiological saline. Five mice were collected from each of infection groups on days 7, 14, 21 d and 25 d post-infection, and 5 mice were collected from the control group on the day of oral gavage. The general and focal functional impairment was scored using the Clark scoring method to assess the degree of mouse neurological impairment. Five mice from each of infection groups were sacrificed on days 7, 14, 21 d and 25 d post-infection, and 5 mice from the control group were sacrificed on the day of oral gavage. Mouse brain tissues were sampled, and the pathological changes of brain tissues were dynamically observed using hematoxylin and eosin (HE) staining. Immunofluorescence staining with eosinophilic cationic protein (ECP) and ionized calcium binding adaptor molecule 1 (Iba1) was used to assess the degree of eosinophil infiltration and the counts of microglial cells in mouse brain tissues in each group, and the morphological parameters of microglial cells (skeleton analysis and fractal analysis) were quantified by using Image J software to determine the morphological changes of microglial cells. In addition, the expression of M1 microglia markers Fcγ receptor III (Fcgr3), Fcγ receptor IIb (Fcgr2b) and CD86 antigen (Cd86), M2 microglia markers Arginase 1 (Arg1), macrophage mannose receptor C-type 1 (Mrc1), chitinase-like 3 (Chil3), and phagocytosis genes myeloid cell triggering receptor expressed on myeloid cells 2 (Trem2), CD68 antigen (Cd68), and apolipoprotein E (Apoe) was quantified using real-time quantitative reverse transcription PCR (RT-qPCR) assay in the mouse cerebral cortex of mice post-infection. Results A large number of A. cantonensis larvae were seen on the mouse meninges surface post-infection, and many neuronal nuclei were crumpled and deeply stained, with a large number of bleeding points in the meninges. The median Clark scores of mouse general functional impairment were 0 (interquartile range, 0), 0 (interquartile range, 0.5), 6 (interquartile range, 1.0), 14 (interquartile range, 8.5) points and 20 (interquartile range, 9.0) points in the control group and the 7-d, 14-d, 21-d and 25-d groups, respectively (H = 22.45, P < 0.01), and the median Clark scores of mouse focal functional impairment were 0 (interquartile range, 0), 2 (interquartile range, 2.5), 7 (interquartile range, 3.0), 18 (interquartile range, 5.0) points and 25 (interquartile range, 6.5) points in the control group and the 7-d, 14-d, 21-d and 25-d groups, respectively (H = 22.72, P < 0.01). The mean scores of mice general and focal functional impairment were all higher in the infection groups than in the control group (all P values < 0.05). Immunofluorescence staining showed a significant difference in the eosinophil counts in mouse brain tissues among the five groups (F = 40.05, P < 0.000 1), and the eosinophil counts were significantly higher in mouse brain tissues in the 14-d (3.08 ± 0.78) and 21-d infection groups (5.97 ± 1.37) than in the control group (1.00 ± 0.28) (both P values < 0.05). Semi-quantitative analysis of microglia immunofluorescence showed a significant difference in the counts of microglial cells among the five groups (F = 17.66, P < 0.000 1), and higher Iba1 levels were detected in mouse brain tissues in 14-d (5.75 ± 1.28), 21-d (6.23 ± 1.89) and 25-d infection groups (3.70 ± 1.30) than in the control group (1.00 ± 0.30) (all P values < 0.05). Skeleton and fractal analyses showed that the branch length [(162.04 ± 34.10) μm vs. (395.37 ± 64.11) μm; t = 5.566, P < 0.05] and fractal dimension of microglial cells (1.30 ± 0.01 vs. 1.41 ± 0.03; t = 5.266, P < 0.05) were reduced in mouse brain tissues in the 21-d infection group relative to the control group. In addition, there were significant differences among the 5 groups in terms of M1 and M2 microglia markers Fcgr3 (F = 48.34, P < 0.05), Fcgr2b (F = 55.46, P < 0.05), Cd86 (F = 24.44, P < 0.05), Arg1 (F = 31.18, P < 0.05), Mrc1 (F = 15.42, P < 0.05) and Chil3 (F = 24.41, P < 0.05), as well as phagocytosis markers Trem2 (F = 21.19, P < 0.05), Cd68 (F = 43.95, P < 0.05) and Apoe (F = 7.12, P < 0.05) in mice brain tissues. Conclusions A. cantonensis infections may induce severe pathological injuries in mouse brain tissues that are characterized by massive eosinophil infiltration and persistent activation of microglia cells, thereby resulting in progressive deterioration of neurological functions.

The life view of "human life is the most important" in Traditional Chinese Medicine (TCM) originates from the people-oriented theory of Chinese traditional culture, the benevolence thought of Confucianism, the rebirth thought of Taoism and the compassion thought of Buddhism. Taking the life view of "human life is the most important" as the starting point, it has formed medical ethics thoughts such as the social responsibility of saving the world, the medical practice purpose of treating all patients equally, the meticulous working attitude, the diligent and tireless learning attitude, and the exploration spirit of widely exploring the medical roots, which still has important educational significance. Therefore, the life view of "human life is the most important" should be integrated into the medical ethics education of medical students, and the medical ethics literacy of medical students should be improved through the following ways: strengthen the vocational ideal education of saving the dying and healing the wounded, and enhance the sense of social responsibility of medical students; consolidate the theme of life first classroom education and improve the professional identity of medical students; enrich and innovate the practice forms of protecting life, pay attention to the practicality of medical ethics education.

Objective To investigate the current status of semen testing in the hospitals without assisted reproductive technology in Hu-nan Province,propose improvement strategies to enhance the diagnosis of male infertility and promote reproductive health services in these hospitals.Methods Questionnaire surveys and on-site investigations were conducted to examine the semen testing status in 67 hospitals without assisted reproductive technology in Hunan Province.The existing problems were summarized,and improvement strate-gies were suggested.Results Among the 67 hospitals,59.7％(40/67)performed semen testing.Of these,45％(18/40)possessed dedicated personnel,60％(24/40)possessed staff received relevant training,and 22.5％(9/40)held certificates.Only 30％(12/40)conducted sperm morphology testing,among them 20％(8/40)able to stain and interpret following WHO standards.The hospitals of 37.5％(15/40)used computer-assisted sperm analysis(CASA)systems,and 22.5％(9/40)were equipped with phase-contrast microscopes.30％(12/40)had dedicated examination areas,and 32.5％(13/40)had independent ejaculation rooms,17.5％(7/40)used disposable slides to observe sperm concentration.In 2022,the hospitals of 57.5％(23/40)had an average daily sample volume＜1.The hospital of 67.5％(27/40)performed standard operating procedures,40％(16/40)followed the WHO 5th la-boratory manual for routine testing,15％(6/40)conducted internal quality control,and 12.5％(5/40)participated in external quali-ty assessment(EQA).Another 55％(22/40)wished to participate in EQA.Conclusion The semen testing capacity in the hospitals,in which assisted reproductive technology is not yet carried out currently,urgently requiring multifaceted improvements.The proposed strategies include emphasizing semen testing,establishing reproductive medicine consortia for comprehensive support,establishing a provincial quality control center for EQA,founding a professional committee for a learning platform,offering training to enhance staff expertise,and including the pre-pregnancy semen testing in public health programs.

Objective:To analyze the correlation between the skin temperature changes in the radiation area and the occurrence of radiodermatitis during postoperative radiotherapy for female breast cancer and to explore the application value of skin temperature monitoring in the early warning of radiodermatitis risks.Methods:A total of 103 patients who received three-dimensional conformal radiotherapy after radical mastectomy in the Fourth Hospital of Hebei Medical University were continuously enrolled from May to November, 2022 in this study. Their skin temperature in the radiation area and radiodermatitis were recorded weekly. The relationships between relative skin temperature differences and different grades of radiodermatitis were determined. The optimal cut-off values for grade ≥ radiodermatitis were calculated, and the predictive effect was evaluated using the receiver operating characteristic (ROC) curve. Furthermore, the radiodermatitis risks under different skin temperatures were compared using binary logistic regression.Results:There was a positive correlation between the skin temperature in the radiation field and the grade of radiodermatitis. The optimal cut-off values for the average relative skin temperature difference of the chest wall (under 40 Gy/20 fractions), the maximum relative skin temperature difference of the chest wall (under 40 Gy/20 fractions), and the relative skin temperature difference of the supraclavicular block (under 30 Gy/15 fractions) were 0.45℃, 0.55℃, 0.15℃, respectively. The patients were divided into low- and high-risk groups based on the optimal cut-off values (0.45℃, 0.55℃, and 0.15℃). Binary logistic regression result showed that the risks of grade ≥ 2 radiodermatitis in the high-risk group were 5.71, 4.29, and 5.15 times those in the low-risk group, respectively ( OR = 5.71, 95% CI 1.81-17.99, P = 0.003; OR = 4.29, 95% CI 1.65-11.12, P = 0.003; OR = 5.15, 95% CI 2.16-12.31, P < 0.001). Conclusions:Skin temperature monitoring using medical infrared thermometers can be used to effectively predict the occurrence of grade ≥ 2 radiodermatitis. The skin temperature changes in the radiotherapy area should be closely observed. The risk of grade ≥ 2 radiodermatitis will increase when the mean and maximum relative temperature differences of the chest wall increase by 0.45℃ and 0.55℃, respectively under 40 Gy/20 fractions of radiotherapy or when the relative temperature differences of the supraclavicular block increases by 0.15℃ under 30 Gy/15 fractions of radiotherapy.

Objective:To report the results of national surveillance on the distribution and antimicrobial resistance profile of clinical Gram-negative bacteria isolates from bloodstream infections in China in 2022.Methods:The clinical isolates of Gram-negative bacteria from blood cultures in member hospitals of national bloodstream infection Bacterial Resistant Investigation Collaborative System（BRICS）were collected during January 2022 to December 2022. Antibiotic susceptibility tests were conducted by agar dilution or broth dilution methods recommended by Clinical and Laboratory Standards Institute（CLSI）. WHONET 5.6 and SPSS 25.0 software were used to analyze the data.Results:During the study period，9 035 strains of Gram-negative bacteria were collected from 51 hospitals，of which 7 895（87.4%）were Enterobacteriaceae and 1 140（12.6%）were non-fermenting bacteria. The top 5 bacterial species were Escherichia coli（ n=4 510，49.9%）， Klebsiella pneumoniae（ n=2 340，25.9%）， Pseudomonas aeruginosa（ n=534，5.9%）， Acinetobacter baumannii complex（ n=405，4.5%）and Enterobacter cloacae（ n=327，3.6%）. The ESBLs-producing rates in Escherichia coli， Klebsiella pneumoniae and Proteus spp. were 47.1%（2 095/4 452），21.0%（427/2 033）and 41.1%（58/141），respectively. The prevalence of carbapenem-resistant Escherichia coli（CREC）and carbapenem-resistant Klebsiella pneumoniae（CRKP）were 1.3%（58/4 510）and 13.1%（307/2 340）；62.1%（36/58）and 9.8%（30/307）of CREC and CRKP were resistant to ceftazidime/avibactam combination，respectively. The prevalence of carbapenem-resistant Acinetobacter baumannii（CRAB）complex was 59.5%（241/405），while less than 5% of Acinetobacter baumannii complex was resistant to tigecycline and polymyxin B. The prevalence of carbapenem-resistant Pseudomonas aeruginosa（CRPA）was 18.4%（98/534）. There were differences in the composition ratio of Gram-negative bacteria in bloodstream infections and the prevalence of main Gram-negative bacteria resistance among different regions，with statistically significant differences in the prevalence of CRKP and CRPA（ χ2=20.489 and 20.252， P<0.001）. The prevalence of CREC，CRKP，CRPA，CRAB，ESBLs-producing Escherichia coli and Klebsiella pneumoniae were higher in provinicial hospitals than those in municipal hospitals（ χ2=11.953，81.183，10.404，5.915，12.415 and 6.459， P<0.01 or <0.05），while the prevalence of CRPA was higher in economically developed regions（per capita GDP ≥ 92 059 Yuan）than that in economically less-developed regions（per capita GDP <92 059 Yuan）（ χ2=6.240， P=0.012）. Conclusions:The proportion of Gram-negative bacteria in bloodstream infections shows an increasing trend，and Escherichia coli is ranked in the top，while the trend of CRKP decreases continuously with time. Decreasing trends are noted in ESBLs-producing Escherichia coli and Klebsiella pneumoniae. Low prevalence of carbapenem resistance in Escherichia coli and high prevalence in CRAB complex have been observed. The composition ratio and antibacterial spectrum of bloodstream infections in different regions of China are slightly different，and the proportion of main drug resistant bacteria in provincial hospitals is higher than those in municipal hospitals.

Objective:To analyze the level of interleukin-36(IL-36) family cytokines in peripheral blood, and explore the regulatory role of recombinant human IL-36α in monocyte function in patients with diabetic kidney disease(DKD).Methods:A total of 41 type 2 diabetes mellitus(T2DM) patients, 36 DKD patients, and 20 controls were consecutively enrolled. Plasma and peripheral blood mononuclear cells(PBMCs) were isolated. Enzyme-linked immunosorbent assay(ELISA) was used to measure plasma levels of IL-36α, IL-36β, IL-36γ, and IL-36 receptor antagonist(IL-36Ra). PBMCs were sorted, and real-time quantitative PCR was performed to detect the mRNA expression of IL-36 receptor subunits in monocytes. Monocytes were stimulated with recombinant IL-36α, and levels of cytotoxic molecules and cytokines in the culture supernatant were measured. Flow cytometry was used to assess the expressions of programmed death receptor-1(PD-1) and cytotoxic T-lymphocyte-associated protein 4(CTLA-4). Co-culture of monocytes with Vero cells was performed to evaluate monocyte cytotoxicity.Results:Plasma levels of IL-36α and IL-36β in the T2DM and DKD groups were significantly higher than those in the control group. The DKD group also showed higher plasma levels of IL-36α compared to the T2DM group( P<0.05). There were no significant differences in IL-36γ and IL-36Ra levels among the three groups( P>0.05). The mRNA expression of IL-36 receptor subunits in monocytes was comparable among the three groups( P>0.05). The DKD group had higher level of tumor necrosis factor-alpha(TNF-α) compared to the control and T2DM groups( P<0.05). The levels of PD-1 and CTLA-4 were lower in the DKD group than those in the control and T2DM groups( P<0.05). The proportion of monocyte-induced Vero cell death was significantly higher in the DKD group compared to the control and T2DM groups( P<0.05). After stimulation with recombinant human IL-36α, monocytes from DKD patients showed a significant increase in the secretion of granzyme B and TNF-α( P<0.05), as well as an increased proportion of monocyte-induced Vero cell death( P=0.024). Conclusion:In DKD patients, elevated IL-36α and granzyme B levels in monocytes enhance monocyte function.

Objective:To investigate interleukin-37 (IL-37) expression in patients with diabetic kidney disease (DKD), and to assess the regulation of exogenous IL-37 on CD8 + T cell function in DKD patients. Methods:A cross-section study was carried out. Twenty healthy controls, thirty-six patients with diabetes mellitus type 2 (T2DM), and forty-seven DKD patients were enrolled in the study. Peripheral blood was collected. Plasma and peripheral blood mononuclear cells were isolated. IL-37 and soluble IL-1 receptor 8 (IL-1R8) levels in the plasma were measured by enzyme-linked immunosorbent assay (ELISA). IL-18 receptor α chain (IL-18Rα), IL-1R8 and immune checkpoint molecules levels in CD8 + T cells were measured by flow cytometry. CD8 + T cells were purified, and were stimulated with recombinant IL-37. CD8 + T cells were co-cultured with HEK293 cells in either direct contact or indirect contact manner. Levels of perforin, granzyme B, interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) were measured by ELISA. The proportion of target cell death was assessed by measuring lactate dehydrogenase level. Results:Plasma IL-37 levels in DKD patients [(63.42±23.30) ng/L] were significant lower than those in healthy controls [(143.02±50.67) ng/L] and T2DM patients [(87.88±40.62) ng/L] ( t=8.848, P<0.001; t=3.456, P<0.001). Plasma IL-37 level had good predictive values for T2DM in health individuals and for DKD in T2DM patients [the area under the curve was 0.797 (95% CI 0.676-0.917, P<0.001) and 0.691 (95% CI 0.576-0.807, P=0.003), respectively]. Plasma IL-37 level was negatively correlated with urea nitrogen ( r=-0.313, P=0.032) and creatinine ( r=-0.477, P<0.001), and positively correlated with estimated glomerular filtration rate (eGFR) ( r s=0.478, P<0.001) in DKD patients. IL-1R8 + CD8 + cell proportion in DKD patients (33.60%±9.47%) was significantly higher compared to healthy controls (16.29%±5.97%) and T2DM patients (17.13%±4.85%) ( t=7.545, 9.516, both P<0.001), but did not correlate with fast blood glucose, urea nitrogen, creatinine, or eGFR (all P>0.05). There were no statistical differences of IL-18Rα + CD8 + cell proportion, soluble IL-1R8 level, or immune checkpoint molecule proportion in CD8 + T cells among healthy controls, T2DM patients, and DKD patients (all P>0.05). Perforin and granzyme B secretions by CD8 + T cells were significantly elevated in DKD patients compared with healthy controls [(108.78±12.42) ng/L vs. (94.60±10.07) ng/L, t=3.096, P=0.005; (261.34±48.79) ng/L vs. (166.28±30.80) ng/L, t=3.387, P=0.002] and T2DM patients [(108.78±12.42) ng/L vs. (92.58±14.71) ng/L, t=3.263, P=0.003; (261.34±48.79) ng/L vs. (170.66±39.24) ng/L, t=2.627, P=0.014]. There were no significant differences of either IFN-γ or TNF-α secretions by CD8 + T cells among healthy controls, T2DM patients, and DKD patients (all P>0.05). In direct contact co-culture manner, CD8 + T cell-induced HEK293 cell death was down- regulated (13.03%±4.97% vs. 17.88%±5.19%, t=2.235, P=0.037). The levels of perforin [(222.02±25.79) ng/L vs. (294.30±25.58) ng/L, t=6.603, P<0.001], granzyme B [(416.27±90.24) ng/L vs. (524.71±115.53) ng/L, t=2.454, P=0.023], IFN-γ [(23.66±4.20) ng/L vs. (35.18±8.51) ng/L, t=4.026, P<0.001] and TNF-α [(1.62±0.29) μg/L vs. (2.09±0.57) μg/L, t=2.302, P=0.034] were also reduced as well. In indirect contact co-culture manner, there were no significant differences of CD8 + T cell-induced HEK293 cell death, perforin, or granzyme B levels between no stimulation and IL-37 stimulation (all P>0.05). IFN-γ and TNF-α levels in the supernatants were reduced in response to IL-37 stimulation [(23.56±6.24) ng/L vs. (32.56±9.90) ng/L, t=2.550, P=0.019; (1.41±0.31) μg/L vs. (2.10±0.44) μg/L, t=4.011, P<0.001]. Conclusion:IL-37 level is reduced in DKD patients.Exogenous IL-37 suppresses the cytotoxicity of CD8 + T cells in DKD patients.

OBJECTIVE To explore the role of clinical pharmacists in identifying paroxysmal spasms caused by drugs， and provide reference for rational drug use. METHODS Retrospective analysis was conducted on pharmaceutical care provided by clinical pharmacists for a patient with ceftazidime-avibactam （CZA-AVI） induced paroxysmal spasms. The clinical pharmacists identified， analyzed and summarized the clinical manifestations， risk factors and treatment methods of the nervous system toxicity caused by antibacterial drugs. According to the patient’s clinical symptoms and test results， the clinical pharmacists recommended temporarily discontinuing the use of polymyxin B and montelukast sodium， and halving the dose of CZA-AVI. The physicians did not adopt the recommendation to halve the dose of CZA-AVI， and when the patient’s neurologic toxicity did not improve， the clinical pharmacists again recommended discontinuing CZA-AVI， which was accepted by the physicians. RESULTS Clinical pharmacists analyzed the condition and checked related drugs that caused paroxysmal spasms of extremities one by one， and finally determined that CZA-AVI might be the drug that caused paroxysmal spasms of extremities in the patient. After stopping the drug， the patient’s symptoms improved and was transferred to a community hospital for rehabilitation treatment. CONCLUSIONS The dose of CZA-AVI should be adjusted according to the renal function and the neurotoxicity should be guarded against， especially for patients with advanced age， renal insufficiency， and the combined use of multiple drugs related to nephrotoxicity and neurotoxicity.

Objective We aimed to investigate the hemostatic effect and mechanism of modified Sijunzi Decoction(MSJZT),consisting of tangshen,India bread,largehead atractylodes rhizome,liquorice root,milkvetch root,ass hide glue,and India madder root,on the zebrafish intestinal bleeding model through 5-hydroxytryptamine(5-HT)and its receptors(5-HT2aR,5-HT2bR).Methods Zebrafish at 4 days post fertilization were used as the research object.An intestinal bleeding model was established by induction with 6 μmol/L simvastatin for 24 hours.The zebrafish were divided into normal group,model group,MSJZT low-,mid-and high-concentration groups(55.6,167,500 mg/L),and after modeling,the corresponding concentration of MSJZT was administered.The samples were collected after 24 hours.Platelet count(PLT)and bleeding status were observed.The content of 5-HT and Caspase 3/7 activity were detected by colorimetry.The gene expressions of 5-HT2aR,5-HT2bR and serotonin transporter(SERT)were detected by real-time PCR.The protein expressions of protein kinase B(AKT),phosphorylated AKT(p-AKT),extracellular signal-regulated protein kinase(ERK),and phosphorylated ERK(p-ERK)were detected by Western blotting.Results The intestinal bleeding rate in the model group was 70.0%,and that in the MSJZT low-,mid-and high-concentration groups was 36.7%,40.0%,and 80.0%,respectively;the intestinal hemostatic effect was 54%,52%,and 7%,respectively.Compared with the model group,the PLT in the MSJZT low-and mid-concentration groups decreased;the content of 5-HT in all MSJZT groups increased,and the gene expressions of 5-HT2aR and 5-HT2bR were up-regulated.The gene expression of SERT was up-regulated in the low-and mid-concentration groups;the Caspase 3/7 activity in the mid-and high-concentration groups was reduced;the expressions of p-AKT and p-ERK proteins were up-regulated in the low-and mid-concentration groups(all P<0.05).Conclusion MSJZT can reduce the incidence and severity of intestinal bleeding in zebrafish intestinal bleeding models.The mechanism may be achieved by activating AKT and ERK signaling pathways through 5-HT and its receptors.