Development of nanobodies specific to clumping factors A of Staphylococcus aureus by yeast surface display.

The Staphylococcus aureus clumping factor A (ClfA) is a fibrinogen (Fg) binding protein that plays an important role in the clumping of S. aureus in blood plasma. The current anti-infective approaches targeting ClfA are mainly based on monoclonal antibodies but showed less impressive efficacy for clinical applications. Nanobodies offer advantages in enhanced tissue penetration and a propensity to bind small epitopes. However, there is no report on generating specific nanobodies for ClfA. Here, we constructed a synthetic nanobody library based on yeast surface display to isolate nanobodies against the Fg binding domain ClfA221-550. We firstly obtained a primary nanobody directed to ClfA221-550, and then employed error-prone mutagenesis to enhance its binding affinity. Finally, 18 variants were isolated with high affinities (EC50, 1.1 ± 0.1 nM to 4.8 ± 0.3 nM), in which CNb1 presented the highest inhibition efficiency in the adhesion of S. aureus to fibrinogen. Moreover, structural simulation analysis indicated that the epitope for CNb1 partially overlapped with the binding sites for fibrinogen, thus inhibiting ClfA binding to Fg. Overall, these results indicated that the specific nanobodies generated here could prevent the adhesion of S. aureus to fibrinogen, suggesting their potential capacities in the control of S. aureus infections.

I Know Some People: The Association of Social Capital With Primary Health Care Utilization of Residents in China.

Background: Primary health care (PHC) services are underused due to the unbalanced distribution of medical resources. This is especially true in developing countries where the construction of PHC systems has begun to take effect. Social capital is one of the important factors affecting primary health care utilization. Method: This study investigated the utilization of PHC services by Chinese community residents in the past year. Social capital, PHC utilization, age, health care insurance, etc., were measured. A multilevel negative binomial model was adopted to analyze the association of social capital with PHC utilization. Results: Data of 5,471 residents from 283 communities in China were collected through a questionnaire survey in 2018. The results showed that community social capital (CSC) is significantly associated with PHC utilization in China, but individual social capital (ISC) had no significant association with PHC utilization. A one-standard deviation increase in the CSC leads to a 1.9% increase in PHC utilization. Other factors like gender, education, income, health insurance, health status, etc., are significantly associated with PHC utilization in China. Conclusions: Community social capital plays a more important role in promoting PHC utilization, while ISC plays an unclear role in PHC utilization by the residents of China.

Patient Preferences for Diabetes Treatment Among People With Type 2 Diabetes Mellitus in China: A Discrete Choice Experiment.

INTRODUCTION: Preferences for diabetes treatment-related attributes may be significant in diabetes management. However, there is a lack of evidence on patient preferences for diabetes in China. METHODS: A large-scale questionnaire survey was conducted in the hospitals of mainland China. Participants' preferences for six attributes were evaluated via a discrete choice experiment (DCE) using the conditional logit model. Patients' willingness to pay (WTP) for each attribute was calculated based on the cost attribute. RESULTS: The sample consisted of 709 patients (male 51.9%; female 48.1%). The results of the model indicated that patients' preference weight (PW) of days on which the blood glucose level is under control per week was the highest (1.41), and the PW of blood glucose monitoring frequency was the lowest (0.642). Patients were generally willing to pay for improvements in their type 2 diabetes mellitus (T2DM) treatment, and they had relatively higher WTP to avoid the blood glucose level within a normal value of 1 day/week (¥176.01) and also to avoid the frequency of hypoglycemic events within the range of 1-2/month (¥144.53). CONCLUSION: The number of days on which the blood glucose level is under control per week is the most important attribute in the treatment choice for patients with T2DM in China, followed by the frequency of hypoglycemic events, medication regimen, weight change, and blood glucose monitoring.

Evaluation of the association between presenteeism and perceived availability of social support among hospital doctors in Zhejiang, China.

BACKGROUND: This study investigated the association between presenteeism and the perceived availability of social support among hospital doctors in China. METHODS: A questionnaire was administered by doctors randomly selected from 13 hospital in Hangzhou China using stratified sampling. Logit model was used for data analysis. RESULTS: The overall response rate was 88.16%. Among hospital doctors, for each unit increase of the perceived availability of social support, the prevalence of presenteeism was decreased by 8.3% (OR = 0.91, P = 0.000). In particular, if the doctors perceived availability of appraisal support, belonging support and tangible support as sufficient, the act of presenteeism was reduced by 20.2% (OR = 0.806, P = 0.000) 20.4% (OR = 0.803, P = 0.000) and 21.0% (OR = 0.799, P = 0.000) respectively with statistical differences. CONCLUSION: In China, appraisal support, belonging support and tangible support, compared to other social support, had a stronger negative correlation with presenteeism among hospital doctors. The benefits of social support in alleviating doctors' presenteeism warrant further investigation.

Influence of Primary Health Care Physicians' Perceived Overqualification on Turnover Intention in China.

BACKGROUND: With the aging population and increasing prevalence of chronic disease, the number of primary health care physicians in China is inadequate and physicians' turnover intention is too high. OBJECTIVE: To analyze the status of primary health care physicians' turnover intention in China and the relationship between physicians' perceived overqualification and their turnover intention. METHODS: With multistage stratified sampling, we randomly selected 1456 primary health care physicians as study subjects. Information on personal characteristics, job satisfaction, working pressure, turnover intention, and perceived overqualification was collected. The data were analyzed using descriptive statistics and multiple regression analysis. RESULTS: We found that primary health care physicians in China have high turnover intention and perceived overqualification is positively related to turnover intention. CONCLUSION: Government and primary health care may address perceived overqualification to reduce physicians' turnover intention.

Human milk microbiota development during lactation and its relation to maternal geographic location and gestational hypertensive status.

Bacteria in human milk could directly seed the infant intestinal microbiota, while information about how milk microbiota develops during lactation and how geographic location, gestational hypertensive status, and maternal age influence this process is limited. Here, we collected human milk samples from mothers of term infants at the first day, 2 weeks, and 6 weeks postpartum from 117 longitudinally followed-up mothers (age: 28.7 ± 3.6 y) recruited from three cities in China. We found that milk microbial diversity and richness were the highest in colostrum but gradually decreased over lactation. Microbial composition changed across lactation and exhibited more discrete compositional patterns in 2-week and 6-week milk samples compared with colostrum samples. At phylum level, the abundance of Proteobacteria increased during lactation, while Firmicutes showed the opposite trend. At genus level, Staphylococcus, Streptococcus, Acinetobacter, Pseudomonas, and Lactobacillus were predominant in colostrum samples and showed distinct variations across lactation. Maternal geographic location was significantly associated with the milk microbiota development and the abundance of predominant genus. In addition, milk from mothers with gestational prehypertension had a different and less diverse microbial community at genus level in early lactation times, and contained less Lactobacillus in the 2-week milk samples than those from normotensive mothers. Findings of our study outlined the human milk microbial diversity and community development over lactation, and underscored the importance of maternal geographic locations and gestational hypertensive status on milk microbiota, which might have important implications in the establishment of the infant intestinal microbiota via breastfeeding.

Associations between social capital and trust in general practitioners among the elderly people: Empirical evidence from China.

Elderly individuals' trust in general practitioners (GPs) is conducive to enhancing their health outcomes and promote healthy ageing. However, this trust has been declining in recent decades. Social capital is associated with patients' trust in healthcare providers in several countries, which make it a potential path for improving the trust of the elderly people in GPs in China, but it is not yet validated. The objective of this study was to explore how social capital influences elderly individuals' trust in GPs in China. The data were collected through a survey conducted with 2,754 people aged 60 and over in China, 2018. Multilevel regression models were employed to analyse the impact of social capital on the trust of the elderly people in GP in China. The results revealed that individual social capital (ISC) and community social capital (CSC) had significant positive correlations with the trust of the elderly people in GPs in China. In addition, CSC has more impact than ISC on the trust of the elderly people in GP. Additionally, older people, women and patients whose highest level of education was junior high school and who had participated in the New Cooperative Medical Scheme tended to have higher trust in GPs. In conclusion, more social capital, especially CSC, contributed more trust of the elderly people in GPs in China.

Identification and characterization of a novel group of natural anti-sense transcripts from RNA1.2 gene locus of human cytomegalovirus.

BACKGROUND: Natural anti-sense transcripts (NATs), which are transcribed from the complementary DNA strand of annotated genes, exert regulatory function of gene expression. Increasing studies recognized anti-sense transcription widespread throughout human cytomegalovirus (HCMV) genome, whereas the anti-sense transcription of RNA1.2 gene locus has never been investigated. In this study, the transcription of the RNA1.2 anti-sense strand was investigated in clinically isolated HCMV strain. METHODS: Strand-specific high-through RNA-sequencing (RNA-seq) was performed to find possible anti-sense transcripts (ASTs). For analyzing and visualization of RNA-seq data sets, Integrative Genomics Viewer software was applied. To confirm these possibilities, Northern blotting and rapid amplification of cDNA ends (RACE) were used. RESULTS: Transcription of the opposite strand of RNA1.2 gene locus was detected by RNA-sequencing using RNAs extracted from human embryonic lung fibroblasts infected with HCMV clinical isolate HAN. At least three HCMV NATs, named RNA1.2 AST 1, RNA1.2 AST2, and RNA1.2 AST3, were characterized by Northern blotting and RACE analyses. These RNA1.2 ASTs orientated from the complementary strand of RNA1.2 locus during the late phase of HCMV infection. The 5'- and 3'-termini of these transcripts were located within the opposite sequence of the predicted RNA1.2 gene. CONCLUSION: A cluster of novel NATs was transcribed from the opposite sequence of the HCMV RNA1.2 gene region.

Endogenously Synthesized n-3 Polyunsaturated Fatty Acids in Pregnant fat-1 Mice Decreases Mammary Cancer Risk of Female Offspring by Regulating Expression of Long Noncoding RNAs.

SCOPE: The present study investigates the precise mechanism by which maternal n-3 PUFAs decrease mammary cancer risk of offspring in terms of epigenetics. METHODS AND RESULTS: Transgenic fat-1 and wild-type C57BL/6J littermates are fed an n-6 PUFAs diet during pregnancy. Wild-genotype offspring of fat-1 mothers (fat-1 group) are compared with wild-genotype offspring of C57BL/6J mothers (control group) in breast cancer risk. Fat-1 group shows a significantly lower tumor incidence and smaller tumor volume compared with control group. n-3 PUFAs in fat-1 mothers change the expression of long noncoding RNA (lncRNA, 53 upregulated and 45 downregulated) in mammary glands of offspring. The lncRNA changes are associated with the changes of mRNA in multiple oncogenic signaling pathways, especially NF-κB, Jak-STAT, and MAPK pathways. Expression of key protein in these pathways, namely p65, p60, STAT3, Jak1, and p38, are significantly inhibited in fat-1 group. In line with these results, reduced proliferation and increased apoptosis are also observed in mammary epithelial of fat-1 group than control group. CONCLUSION: The anticancer effect of maternal n-3 PUFAs is related to the regulation of lncRNA expression, which can further regulate the susceptibility of offspring to breast cancer.

Maternal exposure to an n-3 polyunsaturated fatty acid diet decreases mammary cancer risk of female offspring in adulthood.

Maternal exposure to dietary factors during pregnancy influences the risk of many adult-onset diseases in the later life of offspring. Here, we investigated the effects of maternal n-3 polyunsaturated fatty acid (PUFA) diet on breast cancer risk of female offspring. Pregnant C57BL/6J mice were fed a normal diet (control group), or a high-fat diet rich in safflower oil (SO), fish oil (FO) or flaxseed oil (FSO) (n = 10) throughout gestation and lactation. Their female offspring were fed an AIN-93G diet from weaning. Tumor incidences in offspring induced by 7,12-dimethylbenz[α]anthracene (DMBA) were higher in high-fat groups than in the control group, and were lower in FO and FSO groups than in the SO group. The plasma concentrations of 17ß-estradiol (E2), in both pregnant dams and offspring, were significantly lower in FO and FSO groups compared with the SO group. The FO and FSO offspring showed delayed puberty onset, and their mammary glands contained decreased numbers of epithelial terminal end buds (TEBs, targets for malignant transformation) compared with SO offspring. Reduced cell proliferation and increased apoptosis in FO and FSO offspring were observed compared with SO offspring. In line with these changes, maternal exposure to FO promoted the expression of long noncoding RNA (lncRNA) in p53 and apoptosis signaling pathways and inhibited that in NF-κB and Jak-STAT signaling pathways, while FSO promoted the expression of lncRNA in p53 signaling pathways and inhibited that in NF-κB, Jak-STAT and MAPK signaling pathways. In conclusion, maternal exposure to a high-fat diet rich in n-3 PUFAs, both marine- and plant-based, has a protective effect on mammary tumor risk of female offspring in later life.

Epidermal growth factor and transforming growth factor-α in human milk of different lactation stages and different regions and their relationship with maternal diet.

Epidermal growth factor (EGF) and transforming growth factor-α (TGF-α) are important growth-promoting factors in human milk and play an important role in a newborn's gastrointestinal function. The aim of the present study was to compare EGF and TGF-α contents in breast milk from different lactation periods and different regions and further analyze the effect of maternal diet on the concentration of EGF and TGF-α in breast milk. Breast milk samples and 24-hour food records were obtained from lactating mothers on day 1 (colostrum), day 14 (transitional milk) and day 42 (mature milk) from Hangzhou (n = 76), Lanzhou (n = 76) and Beijing (n = 76), China. EGF and TGF-α levels were determined by enzyme-linked immunosorbent assay (ELISA). The concentration of EGF in breast milk decreased over lactation periods (p < 0.001) while the TGF-α content in breast milk increased over lactation periods (p < 0.001). During all of the three lactation periods, the EGF content in the breast milk from Lanzhou participants was significantly higher than Beijing and Hangzhou participants (p < 0.001), while the TGF-α content in the breast milk from Beijing was significantly higher than that from Lanzhou and Hangzhou (p < 0.001). The concentration of EGF in breast milk decreased with the increasing intake of proteins (p = 0.042), total energy (p = 0.031), vegetables (p = 0.002), fruits (p < 0.001), soy products (p = 0.001) and dairy foods (p < 0.001), while the TGF-α content in breast milk increased with the increasing intake of carbohydrates (p = 0.023) and dairy products (p = 0.011) and decreased with the increasing intake of proteins (p = 0.008) and meat (p = 0.016). The EGF and TGF-α contents in breast milk were greatly influenced by regions and lactation periods and there was also a strong relationship with maternal diet.

Effects of low-fat compared with high-fat diet on cardiometabolic indicators in people with overweight and obesity without overt metabolic disturbance: a systematic review and meta-analysis of randomised controlled trials.

Randomised controlled trials comparing low- v. high-fat diets on cardiometabolic risk factors in people with overweight or obesity have shown inconsistent results, which may be due to the mixed metabolic status of people with excess adiposity. The role of dietary fat manipulation in modifying cardiometabolic indicators in people with overweight or obese without metabolic disturbance is unclear. Thus, meta-analysis was conducted to compare low- v. high-fat diets on cardiometabolic indicators in people who are overweight or obese without metabolic disturbance in the present study. Databases were searched until October 2016. The pooled effects of outcomes with heterogeneity were calculated with a random-effects model, heterogeneities were analysed by subgroup and meta-regression. As a result, twenty studies with 2106 participants were included in the meta-analysis. Total cholesterol and LDL-cholesterol levels were lower following low-fat diets compared with high-fat diets: weighted mean difference (WMD) was -7·05 mg/dl (-0·18 mmol/l; 95 % CI -11·30, -2·80; P=0·001) and -4·41 mg/dl (-0·11 mmol/l; 95 % CI -7·81, -1·00; P=0·011), respectively. Conversely, significant higher level of TAG (WMD: 11·68 mg/dl (0·13 mmol/l), 95 % CI 5·90, 17·45; P<0·001) and lower level of HDL-cholesterol (WMD: -2·57 mg/dl (-0·07 mmol/l); 95 % CI -3·85, -1·28; P<0·001) were found following low-fat diets compared with high-fat diets. In conclusion, dietary fat manipulation has a significant influence on blood lipid levels in people with overweight or obesity without metabolic disturbances.

Concentrations of estrogen and progesterone in breast milk and their relationship with the mother's diet.

The aim of the present study was to determine the concentrations of estradiol (E2), estriol (E3) and progesterone in breast milk over different lactation periods, and to assess their relationship with the mother's diet. Ninety-six breast milk samples as well as 24-hour dietary records from 32 lactating mothers were collected on day 1 (colostrum), day 14 (transitional milk) and day 42 (mature milk) after delivery in Hangzhou, China. The concentrations of E2, E3 and progesterone differed significantly through different periods of lactation (p < 0.001). The content of E2 in colostrum, transitional milk and mature milk was 1.60 ± 0.96 µg L-1, 0.83 ± 0.36 µg L-1 and 1.26 ± 0.48 µg L-1, respectively. The concentrations of E3 were 2.09 ± 1.66 µg L-1, 2.23 ± 1.74 µg L-1 and 4.64 ± 2.15 µg L-1, respectively. The concentrations of progesterone were 6.10 ± 8.30 µg L-1, 4.25 ± 4.76 µg L-1 and 1.70 ± 2.42 µg L-1, respectively. The concentration of progesterone in breast milk was significantly negatively correlated with the intake of protein (p = 0.015), fat (p = 0.008), vegetables (p = 0.012), and meat and eggs (p = 0.036), while the concentration of E3 was significantly positively correlated with the intake of soy products (p = 0.025). This information indicates that the concentrations of E2, E3 and progesterone in breast milk varied over the lactating period. Dietary intake will to some extent affect the contents of E3 and progesterone in breast milk.