Prevalence and influencing factors of depressive and anxiety symptoms among hospital-based healthcare workers during the surge period of the COVID-19 pandemic in the Chinese mainland: a multicenter cross-sectional study

BACKGROUND

From November 2022 to February 2023, the Chinese mainland experienced a surge in COVID-19 infection and hospitalization, and the hospital-based healthcare workers (HCWs) might suffer serious psychological crisis during this period. This study aims to assess the depressive and anxiety symptoms among HCWs during the surge of COVID-19 pandemic and to provide possible reference on protecting mental health of HCWs in future infectious disease outbreaks.

METHODS

A multicenter cross-sectional study was carried out among hospital-based HCWs in the Chinese mainland from 5 January to 9 February 2023. The PHQ-9 (nine-item Patient Health Questionnaire) and GAD-7 (seven-item Generalized Anxiety Disorder Questionnaire) were used to measure depressive and anxiety symptoms. Ordinal logistic regression analysis was performed to identify influencing factors.

RESULTS

A total of 6522 hospital-based HCWs in the Chinse mainland were included in this survey. The prevalence of depressive symptoms among the HCWs was 70.75%, and anxiety symptoms was 47.87%. The HCWs who perceived higher risk of COVID-19 infection and those who had higher work intensity were more likely to experience depressive and anxiety symptoms. Additionally, higher levels of mindfulness, resilience and perceived social support were negatively associated with depressive and anxiety symptoms.

CONCLUSION

This study revealed that a high proportion of HCWs in the Chinese mainland suffered from mental health disturbances during the surge of the COVID-19 pandemic. Resilience, mindfulness and perceived social support are important protective factors of HCWs' mental health. Tailored interventions, such as mindfulness practice, should be implemented to alleviate psychological symptoms of HCWs during the COVID-19 pandemic or other similar events in the future.

The axial and sagittal CT values of the 7th thoracic vertebrae in screening for osteoporosis and osteopenia

AIM

To evaluate the difference in computed tomography (CT) attenuation value of different planes of the 7th thoracic vertebra and investigate the efficacy of axial and sagittal vertebral CT measurements in predicting osteoporosis.

MATERIALS AND METHODS

Patients who underwent routine chest CT and dual-energy X-ray absorptiometry (DXA) within 1 month were included in this retrospective study. The CT attenuation values of different planes were compared. Logistic regression and receiver operating characteristic (ROC) were used to analyse the difference of each plane in the diagnosis of osteoporosis.

RESULTS

The study included 1,338 patients (mean age of 61.9±11.9; 54% female). The CT attenuation values decreased successively in the normal group, osteopenia group, and osteoporosis group. The paired t-test results showed that the mid-axial measurements were greater than mid-sagittal measurements, with a mean difference of 9 HU, the difference was statistically significant (p<0.001, 95% confidence interval [CI] = 7.8-10.1). For each one-unit reduction in mid-sagittal CT attenuation value, the risk of osteopenia or osteoporosis increased by 3.6%. To distinguish osteoporosis from non-osteoporosis (osteopenia + normal), the sensitivity was 90% and the specificity was 52.4% at the mid-sagittal threshold of 113.7 HU.

CONCLUSIONS

The CT attenuation values of mid-sagittal plane have higher diagnostic efficacy than axial planes in predicting osteoporosis. For patients with a sagittal CT attenuation value of <113.7 HU in the T7, further DXA examination is warranted.

HMGB1 acts as an agent of host defense at the gut mucosal barrier

Mucosal barriers provide the first line of defense between internal body surfaces and microbial threats from the outside world. ¹ In the colon, the barrier consists of two layers of mucus and a single layer of tightly interconnected epithelial cells supported by connective tissue and immune cells. ² Microbes colonize the loose, outer layer of colonic mucus, but are essentially excluded from the tight, epithelial-associated layer by host defenses. ³ The amount and composition of the mucus is calibrated based on microbial signals and loss of even a single component of this mixture can destabilize microbial biogeography and increase the risk of disease. ^4-7 However, the specific components of mucus, their molecular microbial targets, and how they work to contain the gut microbiota are still largely unknown. Here we show that high mobility group box 1 (HMGB1), the prototypical damage-associated molecular pattern molecule (DAMP), acts as an agent of host mucosal defense in the colon. HMGB1 in colonic mucus targets an evolutionarily conserved amino acid sequence found in bacterial adhesins, including the well-characterized Enterobacteriaceae adhesin FimH. HMGB1 aggregates bacteria and blocks adhesin-carbohydrate interactions, inhibiting invasion through colonic mucus and adhesion to host cells. Exposure to HMGB1 also suppresses bacterial expression of FimH. In ulcerative colitis, HMGB1 mucosal defense is compromised, leading to tissue-adherent bacteria expressing FimH. Our results demonstrate a new, physiologic role for extracellular HMGB1 that refines its functions as a DAMP to include direct, virulence limiting effects on bacteria. The amino acid sequence targeted by HMGB1 appears to be broadly utilized by bacterial adhesins, critical for virulence, and differentially expressed by bacteria in commensal versus pathogenic states. These characteristics suggest that this amino acid sequence is a novel microbial virulence determinant and could be used to develop new approaches to diagnosis and treatment of bacterial disease that precisely identify and target virulent microbes.

The air temperature change effect on water quality in the Kvarken Archipelago area

The Kvarken Archipelago is Finland's World Heritage site designated by UNESCO. How climate change has affected the Kvaken Archipelago remains unclear. This study was conducted to investigate this issue by analyzing air temperature and water quality in this area. Here we use long-term historical data sets of 61 years from several monitoring stations. Water quality parameters included chlorophyll-a; total phosphorus; total nitrogen; coliform bacteria thermos tolerant; temperature; nitrate as nitrogen; nitrite-nitrate as nitrogen, and Secchi depth and correlations analysis was conducted to identify the most relevant parameters. Based on the correlation analysis of weather data and water quality parameters, air temperature showed a significant correlation with water temperature (Pearson's correlations = 0.89691, P < 0.0001). The air temperature increased in April (R² (goodness-of-fit) = 0.2109 &P = 0.0009) and July (R² = 0.1207 &P = 0.0155) which has indirectly increased the chlorophyll-a level (e.g. in June increasing slope = 0.39101, R² = 0.4685, P < 0.0001) an indicator of phytoplankton growth and abundance in the water systems. The study concludes that there might be indirect effects of the likely increase in air temperature on water quality in the Kvarken Archipelago, in particular causing water temperature and chlorophyll-a concentration to increase at least in some months.

Effects of α-Fe2O3 nanoparticles and biochar on plant growth and fruit quality of muskmelon under cadmium stress

Cadmium pollution in farmland has become a global environmental problem, threatening ecological security and human health. Biochar is effective in remediation of soil pollution. However, high concentrations of biochar can inhibit plant growth, and low concentrations of biochar have limited mitigation effect on cadmium toxicity. Therefore, the combination of low-concentration biochar and other amendments is a promising approach to alleviate cadmium toxicity in plants and improve the safety of edible parts. In this study, muskmelon was selected as the research object, and different concentrations of α-Fe₂O₃ nanoparticles were used alone or combined with biochar to explore the effects of different treatments on muskmelon plants in cadmium-contaminated soil. The results showed that the combined application of 250 mg/kg α-Fe₂O₃ nanoparticles and biochar had a good effect on the repair of cadmium toxicity in muskmelon plants. Compared with cadmium treatment, its application increased plant height by 32.53%, cadmium transport factor from root to stem decreased by 32.95%, chlorophyll content of muskmelon plants increased by 14.27%, and cadmium content in muskmelon flesh decreased by 18.83%. Moreover, after plant harvest, soil available cadmium content in 250 mg/kg α-Fe₂O₃ nanoparticles and biochar combined treatment decreased by 31.18% compared with cadmium treatment. The results of this study provide an effective reference for the composite application of different exogenous amendments and a feasible idea for soil heavy metal remediation and mitigation of cadmium pollution in farmland.

Transcriptome studies on cadmium tolerance and biochar mitigating cadmium stress in muskmelon

Cadmium pollution in agricultural soil is a great threat to crop growth and human health. In this research, with 1%, 3% and 5% biochar applied to control soil cadmium pollution, melon was selected to be the experimental object for physiological detection and transcriptome analysis, through which we explored the mechanism of cadmium tolerance and biochar mitigating cadmium stress in muskmelon. Three set concentrations of biochar have a mitigative effect on muskmelon cadmium stress, and 5% biochar and 3% biochar respectively have the best and the worst alleviative effect. The alleviation of biochar to cadmium stress on muskmelon is primarily in the manner of inhibiting cadmium transfer, while the resistance of muskmelon to cadmium stress is through activating phenylpropanoid pathway and overexpressing stress related genes. Under cadmium treatment, 11 genes of the phenylpropane pathway and 19 stress-related genes including cytochrome P450 family protein genes and WRKY transcription factor genes were up-regulated, while 1%, 3%, 5% biochar addition significantly downregulated 3, 0, 7 phenylpropane pathway genes and 17, 5, 16 stress-related genes, respectively. Genes such as cytochrome P450 protein family genes, WRKY transcription factor genes, and annexin genes may play a key role in muskmelon's resistance to cadmium stress. The results show the key pathways and genes of cadmium stress resistance and the effect of different concentrations of biochar in alleviating cadmium stress, which provide a reference for the research of cadmium stress resistance in crops and the application of biochar in cadmium pollution in agricultural soil.

Difference in general practice telehealth utilisation associated with birth country during COVID-19 from two Australian states

Objective

Telehealth has been an integral part of ensuring continued general practice access during the COVID-19 pandemic. Whether telehealth was similarly adopted across different ethnic, cultural, and linguistic groups in Australia is unknown. In this study, we assessed how telehealth utilisation differed by birth country.

Methods

In this retrospective observational study, electronic health record data from 799 general practices across Victoria and New South Wales, Australia between March 2020 to November 2021 were extracted (12,403,592 encounters from 1,307,192 patients). Multivariate generalised estimating equation models were used to assess the likelihood of a telehealth consultation (against face-to-face consultation) by birth country (relative to Australia or New Zealand born patients), education index, and native language (English versus others).

Results

Patients born in Southeastern Asia (aOR: 0.54; 95% CI: 0.52-0.55), Eastern Asia (aOR: 0.63; 95% CI: 0.60-0.66), and India (aOR: 0.64; 95% CI: 0.63-0.66) had a lower likelihood of having a telehealth consultation compared to those born in Australia or New Zealand. Northern America, British Isles, and most European countries did not present with a statistically significant difference. Additionally, higher education levels (aOR: 1.34; 95% CI: 1.26-1.42) was associated with an increase in the likelihood of a telehealth consultation, while being from a non-English-speaking country was associated with a reduced likelihood (aOR: 0.83; 95% CI: 0.81-0.84).

Conclusions

This study provides evidence showing differences in telehealth use associated with birth country. Strategies to ensure continued healthcare access for patients, whose native language is not English, such as providing interpreter services for telehealth consultations, would be beneficial.

Perspectives

Understanding cultural and linguistic differences may reduce health disparities in telehealth access in Australia and could present an opportunity to promote healthcare access in diverse communities.

Biochar and nano-ferric oxide synergistically alleviate cadmium toxicity of muskmelon

Cadmium is toxic to plants. The accumulation of cadmium in edible plants such as muskmelon may affect the safe production of crops and result in human health problem. Thus effective measures are urgently needed for soil remediation. This work aims to investigate the effects of nano-ferric oxide and biochar alone or mixture on muskmelon under cadmium stress. The results of growth and physiological indexes showed that compared with the application of cadmium alone, the composite treatment (biochar and nano-ferric oxide) decreased malondialdehyde content by 59.12% and ascorbate peroxidase activity increased by 276.6%. Their addition can increase the stress resistance of plants. The results of soil analysis and cadmium content determination in plants showed that the composite treatment was beneficial to reduce the cadmium content in various parts of muskmelon. In the presence of high concentration of cadmium, the Target Hazard Quotient value of peel and flesh of muskmelon in the composite treatment was less than 1, which means the edible risk was greatly reduced. Furthermore, the addition of composite treatment increased the content of effective components; the contents of polyphenols, flavonoids, and saponins in the flesh of the compound treatment were increased by 99.73%, 143.07%, and 18.78% compared with the cadmium treatment. The results provide a technical reference for the further application of biochar combined with nano-ferric oxide in the field of soil heavy metal remediation, and provide a theoretical basis for further research on reducing the toxicity of cadmium to plants and improving the edible quality of crops.

Genetic mapping of a single nuclear locus determines the white flesh color in watermelon (Citrullus lanatus L.)

INTRODUCTION

Flesh color is an important trait in watermelon (Citrullus lanatus L.). Several flesh color genes have been identified in watermelon; however, the inheritance of and the molecular basis underlying the white flesh trait remain largely unknown.

METHODS

In this study, segregation populations were constructed by crossing the canary yellow flesh line HSH-F with the white flesh line Sanbai to fine-map the white flesh gene in watermelon.

RESULTS

Genetic analysis indicated that the white flesh trait is controlled by a single recessive locus, termed Clwf2. Map-based cloning delimited the Clwf2 locus to a 132.3-kb region on chromosome 6. The candidate region contains 13 putative genes, and four of them-Cla97C06G121860, Cla97C06G121880, Cla97C06G121890, and Cla97C06G121900-were significantly downregulated in the white flesh compared to the canary yellow flesh watermelon fruits. The Cla97C06G121890 gene, which encodes a tetratricopeptide repeat protein, showed almost no expression in the white flesh fruit before maturity, whereas it had a very high expression in the canary yellow flesh fruit at 18 days after pollination. Transmission electron microscopy revealed rounded and regularly shaped chromoplasts in both the canary yellow and white flesh fruits. Further quantitative real-time PCR analysis showed that the expression levels of several key plastid division genes and almost the entire carotenoid biosynthesis pathway genes were downregulated in the white flesh compared to the canary yellow flesh fruits.

DISCUSSION

This study suggests that the proliferation inhibition of chromoplasts and downregulation of the CBP genes block the accumulation of carotenoids in watermelon and lead to white flesh. These findings advance and extend the understanding of the molecular mechanisms underlying white flesh trait formation and carotenoid biosynthesis in watermelon.

Comparative clinical outcomes and predictive biomarkers of sintilimab combinations vs. single therapy in cancer: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

This study aimed to compare the efficacy and safety between sintilimab combinations and single treatment in cancer patients, as well as identify biomarkers for selection of patients who might benefit from the combination treatments.

MATERIALS AND METHODS

A search of randomized clinical trials (RCTs) comparing sintilimab combinations vs. single treatment in different tumors according to the PRISMA guidelines was performed. Selected endpoints included completion response rate (CR), objective response rate (ORR), disease control rate (DCR), overall survival (OS), progression-free survival (PFS), major adverse effects (AEs), immune-related adverse events (irAEs). Subgroup analyses based on different combination regimens, tumor type and basic biomarkers were included.

RESULTS

Results reported from 11 RCTs involving 2,248 patients were included in this analysis. Pooled results indicated that both sintilimab plus chemotherapy and sintilimab plus targeted therapy significantly improved CR [RR=2.44, 95% CI (1.14, 5.20), p=0.021; RR=2.91, 95% CI (1.29, 6.57), p=0.010], ORR [RR=1.34, 95% CI (1.13, 1.59), p=0.001; RR=1.70, 95% CI (1.13, 2.56), p=0.011], PFS [HR=0.56, 95% CI (0.43, 0.69), p<0.001; HR=0.56, 95% CI (0.49, 0.64), p<0.001] and OS [HR=0.59, 95% CI (0.48, 0.70), p<0.001]. Subgroup analyses suggested that the sintilimab-chemotherapy group exhibited a superior PFS benefit than the chemotherapy alone group regardless of age, gender, EGOS PS, PD-L1 expression, smoking status, and clinical stage. There were no significant statistical differences in the incidence of any grade and grade 3 or worse AEs between the two groups [RR=1.00, 95% CI (0.91, 1.10), p=0.991; RR=1.06, 95% CI (0.94, 1.20), p=0.352]. While the incidence of any grade irAEs was higher with sintilimab plus chemotherapy as compared to chemotherapy alone (RR=1.24, 95% CI (1.01, 1.54), p=0.044), but no significant difference was found for grade 3 or worse irAEs (RR=1.11, 95% CI (0.60, 2.03), p=0.741).

CONCLUSIONS

Sintilimab combinations brought benefits to a greater number of patients at the cost of a mild increase of irAEs. PD-L1 expression may not be used as a predictive biomarker, composite biomarkers consisting of PD-L1 and MHC class II expression are worth to be explored to enlarge the patient population that benefits from sintilimab combinations.

Enhancing gosling growth and secretion of somatotrophic and thyrotrophic axis hormones through egg turning during incubation

1. Growth performance of Yangzhou geese hatched from eggs with turning angles of 50° or 70° was evaluated in association with serum hormones and somatotrophic gene mRNA expression.2. Egg turning at 70° significantly (P< 0.05) increased hatchability, gosling quality and hatching weight. Gosling post-hatch body weight, leg and breast muscle weight in the 70° turning group was significantly heavier until 50 d of age.3. Serum concentrations of GH were significantly higher until 30 d of age in the 70° turning group goslings, and those of IGF-I and T3 were higher from hatching to 50 d of age.4. The mRNA expression of GHRH, pituitary GH, liver and leg muscle IGF-I were all significantly higher at 1 and 30 d of age after hatch, but not at 70 d after hatch, in the 70° turning group.5. Egg turning at 70° during incubation improves embryo and gosling quality and growth performance through up-regulation of gene expression and secretion of somatotrophic axis hormones, GHRH, GH and IGF-I, as well as T3.

Gypsum scale formation and inhibition kinetics with implications in membrane system

Water desalination using membrane technology is one of the main technologies to resolve water pollution and scarcity issues. In the membrane treatment process, mineral scale deposition and fouling is a severe challenge that can lead to filtration efficiency decrease, permeate quality compromise, and even membrane damage. Multiple methods have been developed to resolve this problem, such as scale inhibitor addition, product recovery ratio adjustment, periodic membrane surface flushing. The performance of these methods largely depends on the ability to accurately predict the kinetics of mineral scale deposition and fouling with or without inhibitors. Gypsum is one of the most common and troublesome inorganic mineral scales in membrane systems, however, no mechanistic model is available to accurately predict the induction time of gypsum crystallization and inhibition. In this study, a new gypsum crystallization and inhibition model based on the classical nucleation theory and a Langmuir type adsorption isotherm has been developed. Through this model, it is believed that gypsum nucleation may gradually transit from homogeneous to heterogeneous nucleation when the gypsum saturation index (SI) decreases. Such transition is represented by a gradual decrease of surface tension at smaller SI values. This model assumes that the adsorption of inhibitors onto the gypsum nucleus can increase the nucleus superficial surface tension and prolong the induction time. Using the new model, this study accurately predicted the gypsum crystallization induction times with or without nine commonly used scale inhibitors over wide ranges of temperature (25-90 °C), SI (0.04-0.96), and background NaCl concentration (0-6 mol/L). The fitted affinity constants between scale inhibitors and gypsum show a good correlation with those between the same inhibitors and barite, indicating a similar inhibition mechanism via adsorption. Furthermore, by incorporating this model with the two-phase mineral deposition model our group developed previously, this study accurately predicts the gypsum deposition time on the membrane material surfaces reported in the literature. We believe that the model developed in this study can not only accurately predict the gypsum crystallization induction time with or without scale inhibitors, elucidate the gypsum crystallization and inhibition mechanisms, but also optimize the mineral scale control in the membrane filtration system.

Alkylresorcinol, a biomarker for whole grain intake, and its association with osteoarthritis: the MOST study

INTRODUCTION

Higher intake of fiber has been associated with lower risk of incident symptomatic osteoarthritis (OA). We examined whether levels of alkylresorcinol (AR), a marker of whole grain intake, were associated with OA in subjects in The Multicenter Osteoarthritis (MOST) Study.

METHOD

Knee x-rays and knee pain were assessed at baseline and through 60-months. Stored baseline fasting plasma samples were analyzed for AR homologues (C17:0, C19:0, C21:0, C23:0, C25:0) and total AR levels (AR sum). Two nested case-control studies, one for incident radiographic OA and one for incident symptomatic OA were performed with participants re-assessed at 15, 30 and 60 months. Multivariable conditional logistic regression with baseline covariates including age, sex, BMI, physical activity, quadriceps strength, race, smoking, depressive symptoms, diabetes and knee injury tested the association of log transformed AR levels with OA outcomes.

RESULTS

Seven hundred seventy-seven subjects were, on average, in their 60's, and most were women. For 60-month cumulative incidence, there was no significant association between quartiles of AR concentration and incident radiographic (e.g., for incident radiographic OA, highest vs lowest quartile of AR sum showed RR = 0.93 (95% CI 0.59, 1.47), and for symptomatic OA RR was 1.22 (95% CI 0.76, 1.94). In secondary analyses examining 30-month incidence, high AR levels were associated with a reduced risk of X-ray OA (RR = 0.31 (95% CI 0.15, 0.64).

CONCLUSION

In primary analyses, AR levels were not associated with risk of OA, but secondary analyses left open the possibility that high AR levels may protect against OA.

[Progress and policy considerations on the pilot program of standardized training for public health physicians in China]

The standardized training for public health physicians plays an important role in exploring the cultivation public health professionals and strengthening the construction of public health service providers. In 2018, the National Health Commission of China launched a pilot program of standardized training for public health physicians in 10 provinces. This paper clarifies the definition of the standardized training for public health physicians, systematically analyzes the status quo of the training in China and other countries, articulates the design and progress of the training in the perspective of Centers for Disease Control and Prevention, and makes some suggestions for the priorities of the pilot training program, so as to provide reference and basis for the better development of the standardized training for public health physicians in China in the future.

Assessment of Cd bioavailability using chemical extraction methods, DGT, and biological indicators in soils with different aging times

Total cadmium (Cd) cannot be used to accurately assess the ecological risk of Cd pollution in soil. Currently there is no universally recognized method to evaluate Cd bioavailability in soil. In this study, chemical extraction methods, diffusive gradients in thin films (DGT) and bioindicator methods were used to evaluate Cd bioavailability in soils with the same properties but different aging times. Results indicate that aging decreased the Cd bioavailability in soil and its toxicity to barley. This was primarily due to a decrease in the proportion of ion-exchangeable Cd. Correlation analyses were conducted on the Cd bioavailable content obtained via the soil extraction methods and the toxicity effect of barley. Results showed that the order of the minimum value of the linear regression determination coefficient (R²) of chemical extraction methods and DGT was as follows: DGT-Cd (0.7385, p < 0.05) > total Cd (0.6931, p < 0.05) > acetic acid-Cd (0.6078) > ion-exchangeable Cd (0.5933) > DTPA-Cd (0.5842) > CaCl₂-Cd (0.4980) > water-soluble Cd (0.4602). The order of minimum value of R² of biological indicators of barley was integrated biomarker response (IBR) (0.8501, p < 0.01) > length (0.6492) > dry weight (0.6320) > fresh weight (0.4980) > Cd concentration (0.4602). The root is more suitable for indicating the plant uptake and accumulation of Cd in soil. Meanwhile, the shoot can effectively evaluate the toxic effect of Cd stress on plants. DGT is more suitable to reflect Cd bioavailability to barley compared to chemical extraction methods, Furthermore, it can be used to evaluate stable polluted soil with longer aging time. In the study of the bioavailability of heavy metals in soil, IBR can be used as a reliable reference index to contribute to the comprehensive evaluation of metal bioavailability in addition to considering plant uptake.

[Interference of P2X4 receptor expression in tumor-associated macrophages suppresses migration and invasion of glioma cells]

OBJECTIVE

To investigate the effect of interference of P2X4 receptor expression in tumor-associated macrophages (TAMs) on invasion and migration of glioma cells.

METHODS

C57BL/6 mouse models bearing gliomas in the caudate nucleus were examined for glioma pathology with HE staining and expressions of Iba-1 and P2X4 receptor with immunofluorescence assay. RAW264.7 cells were induced into TAMs using conditioned medium from GL261 cells, and the changes in mRNA expressions of macrophage polarization-related markers and the mRNA and protein expressions of P2X4 receptor were detected with RT-qPCR and Western blotting. The effect of siRNA-mediated P2X4 interference on IL-1β and IL-18 mRNA and protein expressions in the TAMs was detected with RT-qPCR and Western blotting. GL261 cells were cultured in the conditioned medium from the transfected TAMs, and the invasion and migration abilities of the cells were assessed with Transwell invasion and migration experiment.

RESULTS

The glioma tissues from the tumor-bearing mice showed a significantly greater number of Iba-1-positive cells, where an obviously increased P2X4 receptor expression was detected (P=0.001), than the brain tissues of the control mice (P < 0.001). The M2 macrophage markers (Arg-1 and IL-10) and M1 macrophage markers (iNOS and TNF-α) were both significantly up-regulated in the TAMs derived from RAW264.7 cells (all P < 0.01), but the up-regulation of the M2 macrophage markers was more prominent; the expression levels of P2X4 receptor protein and mRNA were both increased in the TAMs (P < 0.05). Interference of P2X4 receptor expression significantly lowered the mRNA(P < 0.01)and protein (P < 0.01, P < 0.05)expression levels of IL-1β and IL-18 in the TAMs and obviously inhibited the ability of the TAMs to promote invasion and migration of the glioma cells (P < 0.05).

CONCLUSION

Interference of P2X4 receptor in the TAMs suppresses the migration and invasion of glioma cells possibly by lowering the expressions of IL-1β and IL-18.

Effects of Cadmium on Physiochemistry and Bioactive Substances of Muskmelon (Cucumis melo L.)

Muskmelon pedicel is the fruit stalk of muskmelon and one of the traditional Chinese medicines, which can be used to treat jaundice, diabetes and neuropathy. However, in recent years, agricultural soil heavy metal cadmium (Cd) pollution has become serious, coupled with the imperfect sales management of herbal medicine, increasing the potential health risk of contaminated herbal medicine in the human body. In this paper, the comprehensive quality of contaminated muskmelon was tested. The results showed that Cd stress significantly inhibited the growth of muskmelon plants, reduced the anthocyanin and chlorophyll contents, and increased the fruit size and sweetness of muskmelon. In addition, heavy metal Cd can also cause oxidative stress in plants, resulting in a series of changes in antioxidant enzyme activities. In the experimental group, the content of polyphenols and saponins increased by 27.02% and 23.92%, respectively, after high-concentration Cd treatment, which may be a mechanism of plant resistance to stress. This paper reveals that the content of bioactive substances in Chinese herbal medicine is high, but the harm in heavy metals cannot be underestimated, which should be paid attention to by relevant departments.

Physiological of biochar and α-Fe2O3 nanoparticles as amendments of Cd accumulation and toxicity toward muskmelon grown in pots

BACKGROUND

Due to the severe cadmium (Cd) pollution of farmland soil, effective measures need to be taken to reduce the Cd content in agricultural products. In this study, we added α-Fe2O3 nanoparticles (NPs) and biochar into Cd-contaminated soil to investigate physiological responses of muskmelon in the whole life cycle.

RESULTS

The results showed that Cd caused adverse impacts on muskmelon (Cucumis melo) plants. For instance, the chlorophyll of muskmelon leaves in the Cd alone treatment was reduced by 8.07-32.34% in the four periods, relative to the control. The treatments with single amendment, α-Fe2O3 NPs or 1% biochar or 5% biochar, significantly reduced the soil available Cd content, but the co-exposure treatments (α-Fe2O3 NPs and biochar) had no impact on the soil available Cd content. All treatments could reduce the Cd content by 47.64-74.60% and increase the Fe content by 15.15-95.27% in fruits as compared to the Cd alone treatment. The KEGG enrichment results of different genes in different treatments indicated that single treatments could regulate genes related to anthocyanin biosynthesis, glutathione metabolism and MAPK signal transduction pathways to reduce the Cd toxicity.

CONCLUSIONS

Overall the combination of biochar and α-Fe2O3 NPs can alleviate Cd toxicity in muskmelon. The present study could provide new insights into Cd remediation in soil using α-Fe2O3 NPs and biochar as amendments.

[Emergency training need and effect evaluation analysis of novel coronavirus pneumonia in centers of disease control and prevention]

A questionnaire was used to investigate the emergency training needs of novel coronavirus pneumonia of disease prevention and control institutions in provinces, deputy provincial level regions and cities specifically designated in the state plan, and the effect evaluation of emergency training activities conducted by Chinese Center for Disease Control and Prevention (China CDC). The results showed that 67.4% of 47 disease prevention and control institutions (31/46) believed that the emergency training at the initial stage of the epidemic should be conducted as soon as possible, and the form of network training should be given priority. The training should focus on the urgently needed technologies such as epidemiological investigation, formulation and response of prevention and control strategies, laboratory testing, etc. The teaching materials should highlight pertinence and practicability and be presented in the form of electronic video. The average satisfaction score of the video training conducted by China CDC was (8.81±1.125) and the score of audio-video courseware was (8.97±0.893). The needs analysis and evaluation of novel coronavirus pneumonia prevention and control in disease prevention and control institutions could provide reference for the follow-up training and improve the emergency training management.

[Current situation and suggestions of public health personnel training in disease control and prevention institutions]

Under the background that the national health has become the national priority development strategy, it is essential to speed up public health ability among talents. Based on the consulting project of the Chinese Academy of Engineering, "Research on the training strategy of medical and health personnel in China", this paper analyzes the current situation and existing problems of public health personnel training in disease control and prevention institutions. Based on three stages of public health education, this paper puts forward that the public health personnel training should first solve the problem of public health personnel team construction and create programs on college education-post graduate education-continuing education. Through the personnel training system, different training modes are designed for other groups of people to improve the ability of public health personnel in an all-around way.

[The Museum of Western Studies on Chinese Medicine:Chinese medicine in the western societies]

The historical artifacts displayed in the Museum of Western study on Chinese Medicine at Yunnan University of Chinese Medicine came from a variety of Chinese medical schools in America and European countries. They are in the memorial galleries for some well-known figures, such as George Soulié de Morant (Su Lie), Jacques-André Lavier (La Wei Ai), Felix Mann (Man Fu Li) and Manfred Porkert (Man Xi Bo), representing the development and status of respective Chinese medical schools in America and European countries. The displayed artifacts are nearly 3,000 photos, manuscripts, documents and more than 500 hours of audiovisual materials, including instruments for acupuncture and moxibustion, books, passports, letters and even supplies for their life. The displayed artifacts demonstrate the process and the access of people in the western societies to know, learn and take use of Chinese medicine.

Copper stimulates neonicotinoid insecticide thiacloprid degradation by Ensifer adhaerens TMX-23

AIMS

Aims of this study are to elucidate the molecular mechanism of copper-improved thiacloprid (THI) degradation by Ensifer adhaerens TMX-23 and characterize copper resistance of this strain.

METHODS AND RESULTS

Resting cells of E. adhaerens TMX-23 were used to degrade THI, with formation of THI amide and 98·31% of 0·59 mmol l^-1 THI was degraded in 100 min. The addition of copper improved the degradation of THI and showed little inhibitory effects on the growth of E. adhaerens TMX-23. E. adhaerens TMX-23 degraded THI to THI amide by nitrile hydratases (NhcA and NhpA). QPCR analysis indicated that the expression of nhpA was up-regulated in the presence of copper. E. adhaerens TMX-23 nitrile hydratases were purified, and enzyme assay of NhpA exhibited the highest NHase activity toward THI. The addition of copper activated the activity of NhcA. Soil degradation experiment indicated that E. adhaerens TMX-23 could quickly eliminate THI residual in copper-added soil.

CONCLUSIONS

Copper improved THI degradation by E. adhaerens TMX-23 was attributed to the induced expression of nhpA and activated NhcA.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study broadens the investigation of regulatory mechanism of NHase expression and provided theoretical basis for using metal-resistant microbes to degrade pesticide in heavy metal co-contaminated environments.

[Survey on provincial disease prevention and control professionals' attitudes and cognition to public health physician standardized training in China]

Objective: To understand the attitudes and cognition of disease control and prevention professionals at provincial level on public health physician standardized training and provide evidence for the improvement of the standardized training and exploration of more effective training mode in China. Methods: By cluster sampling, 2 193 professionals at provincial centers for disease control and prevention (CDC) in 6 provinces, including Jiangsu and Guangdong, Shanxi and Hubei,Sichuan and Xinjiang were selected as the study subjects, the sample size was estimated to be 1 933 persons. Results: A total of 1 716 provincial-level CDC professionals were surveyed, the support rate to the standardized training was 70.7%(1 213/1 716). The level of support was negatively associated with the educational level of professionals and their specialty of public health and preventive medicine. Of 875 public health and preventive medicine professionals, 61.6%(318/516) of those with master's degree or above supported the standard training for public health physicians, which was lower than 73.1%(225/308) of those with bachelor's degree and 86.3%(44/51) of those with college degree or below. There were 14.9%(232/1 555) of the respondents suggested a two year training, and 60.4%(933/1 544) suggesting a field training mode. In terms of training content, 86.6%(1 355/1 564) suggesting "epidemiological survey and public health practice", and 76.7%(1 199/1 564) suggesting "basic theories and methodology". Conclusions: In general, the professionals of provincial CDC showed a relatively low interest in the standardized training for public health physicians and failed to reach a consensus. Besides, they were ill-informed about current training duration, method and content. Thas, the professionals at provincial CDC are suggested to be the key target-population whom should be mobilized during the training pilot period, especially the highly educated ones with relevant specialties of public health. It is suggested that public health physician standardized training should to be implemented in whole CDC system to reach full consensus based on its practical achievements and effects. It is also suggested to establish public health graduate medical education system in China.

Metabolomic evaluation of serum metabolites of geese reared at different stocking densities

1. Stocking density is an issue for poultry production. High stocking density can impact biochemical parameters, production, and reproductive performance; however, information regarding the effects of stocking density on serum metabolites in geese is limited.2. Twenty-day-old, Sanhua male geese (n = 240) were allocated to one of two experimental groups for 50 days. One group was housed under a low stocking density (LSD; two birds per m²) and one under a high stocking density (HSD; five birds per m²). Body weight and feed intake were recorded every 10 d. Eight serum samples per group were used for metabonomic analysis by liquid chromatography-mass spectrometry.3. Stocking density did not affect the spleen, liver, thymus, or bursa of Fabricius weights after 50 d. Feed intake and body weight was significantly lower in geese from the HSD group versus the LSD group (P < 0.05). Thirty-six differential serum metabolites were identified (P < 0.05), indicating altered amino acid, carbohydrate, lipid and vitamin cofactor metabolism.4. The results demonstrated that high-density stocking impacts geese, and provides insights into the mechanisms underlying the adverse health effects associated with HSD.

Percutaneous transluminal septal myocardial ablation markedly reduces energy loss in hypertrophic obstructive cardiomyopathy: a four-dimensional flow magnetic resonance imaging study

Background

Functional follow-up modalities of hypertrophic obstructive cardiomyopathy (HOCM) subjected to percutaneous transluminal septal myocardial ablation (PTSMA) are limited mainly to echocardiography and catheterization. Recent advancements in four-dimensional (4D) flow magnetic resonance imaging (MRI) have enabled us to assess patients from the perspective of fluid dynamics by visualising blood flow and calculating quantitative parameters such as wall shear stress and energy loss within cardiac chambers or blood vessels. Several reports have demonstrated that the intra-cardiac energy loss decreased along with improvement of cardiac function achieved by treatment of cardiac diseases. Whether changes in energy loss occur along with PTSMA in HOCM patients and the underlying mechanism remain unknown.

Purpose

This study sought to investigate the influence of PTSMA in patients with HOCM on energy loss in the left ventricle (LV) and aortic root measured by 4D flow MRI.

Methods

We retrospectively recruited HOCM patients who underwent PTSMA at a referral centre from May to November 2019. Patients who underwent 4D flow MRI both before and after PTSMA were included. We collected demographic and clinical data from electronic health records. MRI scans implemented two-dimensional phase-contrast imaging of the three-chamber plane with three-directional velocity, using a 1.5 T scanner. Furthermore, 4D blood flow analysis was performed on off-line saved data, using iTFlow version 1.9. We assessed energy loss in one cardiac cycle within the three-chamber plane of the LV and aortic root (area surrounded by the LV endocardium, sinotubular junction, and mitral annulus).

Results

This study finally included 12 patients, whose mean age was 66±12 years, and 5 (42%) of whom were men. The pressure gradient between the LV apex and ascending aorta was 81±32 mmHg before and 20±22 mmHg immediately after PTSMA (P&lt;0.005, paired). Before PTSMA, 6 patients were in New York Heart Association functional class III and the other 6 in class II. However, after PTSMA, 10 patients improved to class I and 2 to class II. PTSMA reduced energy loss in one cardiac cycle within the three-chamber plane of the LV and aortic root, from 79±36 mJ/m to 55±19 mJ/m (P=0.001, paired).

Conclusions

PTSMA in patients with HOCM reduced energy loss within the LV and aortic root, indicating significant decrease with cardiac workload. Four-dimensional flow MRI of the three-chamber plane to assess energy loss within the LV and aortic root is a time-efficient and reproducible quantitative method to evaluate the effects of PTSMA. Given its non-invasive nature, it also enables to sequentially follow-up HOCM patients who underwent PTSMA.

Periprocedural changes of energy loss

Funding Acknowledgement

Type of funding source: None

A study on the mixture repairing effect of biochar and nano iron oxide on toxicity of Cd toward muskmelon

Soil contamination with cadmium (Cd) has become a serious problem, adversely affecting food safety and human health. Effective methods are urgently needed to alleviate toxicity of Cd in plants. In this study, a nine-week continuous pot experiments was conducted to explore the effectiveness of the different nano iron oxide (α-Fe₂O₃, γ-Fe₂O₃, Fe₃O₄) alone and combined with biochar in muskmelon grown on a Cd-contaminated soil. The antioxidant system, chlorophyll, soluble protein, other physiological indexes of muskmelon leaves and the distribution of Cd in matrix soil, leaves and fruit were detected. The results showed that Cd was readily absorbed by plants and caused oxidative stress on plants, while biochar, α-Fe₂O₃ nanoparticles (NPs) and their mixture group (BFe1 group) could significantly improve it. Specifically, the three treatments reduced the Cd content of the fruit by 19.51-78.86%, reduced the Cd content of leaves by 15.44-36.23% and 22.36-31.77% in weeks 3 and 5, respectively. For the activity of enzymes, three treatments decreased superoxide dismutase (SOD) activity and catalase (CAT) activity by 3.41-38.57% and 24.27-30.33% in week 7, respectively. So BFe1 group application immobilized Cd in soil and reduced Cd partitioning in the aboveground tissues. Overall the combination of biochar and α-Fe₂O₃ NPs can alleviate Cd toxicity in muskmelon and can protect human beings from Cd exposure.

Overexpression of miR-146a inhibits the apoptosis of hippocampal neurons of rats with cerebral hemorrhage by regulating autophagy

In this study, to investigate the effect of overexpression of miR-146a on autophagy of hippocampal neurons in rats with intracerebral hemorrhage (ICH), 72 Sprague-Dawley rats were randomly divided into the sham, ICH, miR-146a agomir, and miR-146a agomir control groups. The ICH model was constructed by injection of collagenase VII. The apoptosis of hippocampal neurons was measured by TUNEL assay. The levels of LC3 and Beclin 1 were analyzed by immunohistochemistry. Mitochondrial autophagy was examined by transmission electron microscopy. The levels of LC3A, LC3B, Beclin 1, Bax, Bcl-2, and cleaved caspase 3 were examined by Western blot. Western blot was also used to evaluate the expression of nuclear factor κB signaling pathway-related factors. To examine the effect of autophagy inhibitor (3-methyladenine (3-MA)) on miR-146a-regulated apoptotic protein expression, 30 rats were further divided into the sham, ICH, miR-146a agomir, 3-MA, and miR-146a + 3-MA groups. The levels of Bax, Bcl-2, and cleaved caspase 3 were examined by Western blot. Compared with the sham group, the nerve function scores, brain water content, the percentage of apoptotic cells, and the expression levels of LC3, Beclin 1, Bax, cleaved caspase 3, and p-P65 in the hippocampus of rats in the ICH group were all significantly increased (p < 0.05), whereas the expression levels of miR-146a, Bcl-2, and p-IκBα were markedly decreased (p < 0.05). Mitochondrial autophagy was also evident. Furthermore, compared with the ICH group, the results of the abovementioned tests in the miR-146a agomir group were reversed. The overexpression of miR-146a inhibited the autophagy of hippocampal neurons in rats with ICH.

[Reflections on the orientation of public health physicians]

Public health physician is one of the four statutory types of physicians in China, but there is no consensus on their connotation. The main problems are that public health physician is confused with those who perform public health tasks, the relationship between public health physician and clinician and the connotation of prescription right is not clear, and there is limitation in public health education and relevant laws and regulations. Public health physician is positioned as professionals who monitor, investigate, evaluate, and intervene in population health-related issues. It is suggested to retain the practicing qualification of public health physicians and highlight the attribute of public health physicians' prescribing the prescriptions for community health. Encourage public health physicians to obtain qualification for clinicians to individual prescription, Encourage clinicians to access to public health physician qualification. Improve public health school education, take the pilot of public health physician standardization training, cultivate "prevention and treatment combined" physician.

Genome-wide identification of flowering time genes in cucurbit plants and revealed a gene ClGA2/KS associate with adaption and flowering of watermelon

Watermelon (Citrullus lanatus) is one of the major cucurbit crop that cultivated all over the world. Adaptability and flowering time are important agronomic characteristics that influence the quality and yield of watermelon, however, the molecular basis underlying these traits were still unclear. In this study, we identified 166, 182, 178, and 279 flowering genes in watermelon, melon, cucumber and pumpkin, respectively, and found that a lot of genes in the photoperiodic, autonomous, and vernalization pathways were absence in the four cucurbits. A higher ratio of flowering time genes was identified in the hormone pathway in cucurbits than in Arabidopsis, and a higher average ka/ks value of hormone pathway genes than the photoperiodic and vernalization pathway genes was identified in watermelon. Moreover, a gene ClGA2/KS (Cla005482) were found to associated with ecotype differentiation, flowering time, and whole growth period in watermelon. This study added knowledge to the molecular basis of flowering time regulation in cucurbits, and the molecule marker of ClGA2/KS gene may facilitate the breeding progress for selecting watermelon varieties with superior adaption and flowering time.

P1643An exploratory analysis for the optimal monitoring interval of N-terminal pro-B-type natriuretic peptide in patients with stable heart failure

Background

N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a potential biomarker for monitoring the status of heart failure. However, the optimal monitoring interval is unknown. This study aims to investigate minimal informative monitoring interval of NT-proBNP in patients with stable chronic heart failure.

Methods

In this retrospective open cohort study, adult patients followed up at a tertiary hospital for chronic heart failure with NT-proBNP measurements were included if they had been previously admitted due to acute heart failure and were free from readmission over 6 months after discharge. We analyzed NT-proBNP measured between 6 months after discharge and the timepoint of an alteration of medication regimen or readmission due to worsening of heart failure. To distinguish actual progression of the disease from biological variability and measurement error, the signal-to-noise ratio method was applied with a random-effects model. Stratified analysis was performed according to underlying risks.

Results

In this analysis, 368 patients were included with NT-proBNP measured between July 2009 and December 2017. The patients had 6.0 times of NT-proBNP measurements in median (interquartile range [IQR] 4.0–10.0) during the follow-up period (median 12.0 months [IQR 6.0–27.0]). In the estimates of the random-effects model, signal (i.e. actual progression of the disease) exceeded noise (i.e. biological variability and measurement error) at 8.1 months (95% confidence interval [CI]: 5.7–10.1) after the index measurement. In a subgroup analysis according to the AHEAD risk score, the minimal informative monitoring interval was shortened as the risk score increased (0–1 point: 12.3 months [95% CI: 10.3–14.5]; 2–3 points: 8.0 months [95% CI: 6.8–9.7]; 4–5 points: 3.3 months [95% CI: 3.0–3.8]; Figure).

Informative intervals stratified by risk

Conclusion

In patients with stable chronic heart failure, the overall minimal informative monitoring interval of NT-proBNP measurement was 8.1 months, which varies by underlying risk. The optimal monitoring interval could be lengthened especially for patients at lower risk.

Identification of key pathways and genes changes in pancreatic cancer cells (BXPC-3) after cross-talk with primary pancreatic stellate cells using bioinformatics analysis

Pancreatic ductal adenocarcinoma (PDAC) is one of the most malignant tumors with poor prognosis, and the interaction between activated pancreatic stellate cells (PSCs) and PDAC cells plays an important role in the development of PDAC. The aim of this study was to identify gene changes in BXPC-3 after cross-talk with PSCs and reveal their potential mechanisms. The gene expression profiling analysis of BXPC-3 was completed after co-culture with primary PSCs for 48 h. The gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) enrichment analyses were performed, and the differentially expressed genes (DEGs) were identified by Agilent GeneSpring GX software. In total, 3657 DEGs were identified in BXPC-3, including 1881 up-regulated genes and 1776 downregulated genes. GO analysis results showed that upregulated DEGs were significantly enriched in biological processes (BP), including peptide metabolic process, response to stress and electron transport chain; the downregulated DEGs were significantly enriched in biological processes, including signaling, multicellular organism development and anatomical structure development. KEGG pathway analysis revealed that 19 pathways were upregulated and 32 pathways were downregulated, and that upregulated DEGs were enriched in protein export and glutathione metabolism, while the downregulated DEGs were enriched in axon guidance and focal adhesion. The top 10 upregulated genes and the top 10 downregulated genes were identified. By constructing PPI network, we selected out 10 key genes (TP53, SRC, IL6, JUN, ISG15, CAD, STAT1, OAS3, OAS1, VIM) and significant pathways. The associated survival analysis was performed and the SRC, IL-6, ISG15, STAT1, OAS3, OAS1 and VIM were proved to be related to worse overall survival time of PDAC patients. In conclusion, the present study indicated that the identified DEGs promote our understanding of the molecular mechanisms underlying the interaction between pancreatic cancer cells and PSCs and might be used as molecular targets in the future to study the role of tumor microenvironment in the progression of PDAC.

Kaempferol attenuates imiquimod-induced psoriatic skin inflammation in a mouse model

Psoriasis is an immune-mediated inflammatory skin disease that mainly affects the skin barrier. Treatment for psoriasis mainly includes conventional immunosuppressive drugs. However, long-term treatment with global immunosuppressive agents may cause a variety of side effects, including nephrotoxicity and infections. Kaempferol, a natural flavonol present in various plants, is known to possess potent anti-inflammatory, anti-oxidant and anti-cancerous properties. However, it is unknown whether kaempferol is also anti-psoriatic. Here we established an imiquimod (IMQ)-induced psoriatic mouse model to explore the potential therapeutic effects of kaempferol on psoriatic skin lesions and inflammation. In this study, we demonstrated that treatment with kaempferol protected mice from developing psoriasis-like skin lesions induced by topical administration of IMQ. Kaempferol reduced CD3⁺ T cell infiltration and gene expression of major proinflammatory cytokines, including interleukin (IL)-6, IL-17A and tumor necrosis factor (TNF)-α, in the psoriatic skin lesion. It also down-regulated proinflammatory nuclear factor kappa B (NF-κB) signaling in the skin. The therapeutic effects were associated with a significant increase in CD4⁺ forkhead box protein 3 (FoxP3)⁺ regulatory T cell (T_reg ) frequency in the spleen and lymph nodes as well as FoxP3-positive staining in the skin lesion. Conversely, depletion of CD4⁺ CD25⁺ T_regs reversed the therapeutic effects of kaempferol on the skin lesion. Kaempferol also lowered the percentage of IL-17A⁺ CD4⁺ T cells in the spleen and lymph nodes of IMQ-induced psoriatic mice. Finally, kaempferol suppressed the proliferation of T cells in vitro and their mTOR signaling. Thus, our findings suggest that kaempferol may be a therapeutic drug for treating human psoriasis in the near future.

[A survey of attitudes to and demands on internship in graduates majoring in preventive medicine in 6 colleges and universities in China]

Objective: To understand the internship of students majoring in preventive medicine in 6 colleges and universities in China, and provide reference suggestions for the improvement of internship arrangement. Methods: By using the method of combined clustering and convenient sampling, the fifth grades students majoring in preventive medicine in six universities in the eastern, central and western China were surveyed by using questionnaires to collect the information of their attitudes (to) and suggestions for clinical and public health internships. Results: A total of 596 students were surveyed. In terms of the benefits of clinical internship and public health internship, students who thought that the internship was fruitful accounted for >88%, and more students thought that reform is needed in clinical internship compared with public health internship. In clinical internship, the students through that the time arrangement was not appropriate enough (95, 39.58%), the content should be more detailed and in-depth (73, 30.42%) and the content did not conform to the professional direction (54, 22.50%). In public health internship, the students thought that the time arrangement was not appropriate (77, 45.56%), the content should be more detailed and standardized (65, 38.46%) and the types of internship bases should be more diversified (20, 11.83%). Conclusions: The undergraduates majoring in preventive medicine felt to be benefited from clinical practice and public health internships and thought they are of necessity. At the same time, there are still many problems which needs to be improved in the two types of internships. It is necessary to make joint efforts from students, teachers, colleges and practice bases to promote the continuous improvement of undergraduate internship.