Effects of Biochar and Straw Amendment on Soil Fertility and Microbial Communities in Paddy Soils.

Straw and biochar, two commonly used soil amendments, have been shown to enhance soil fertility and the composition of microbial communities. To compare the effects of straw and biochar on soil fertility, particularly focusing on soil dissolved organic matter (DOM) components, and the physiochemical properties of soil and microbial communities, a combination of high-throughput sequencing and three-dimensional fluorescence mapping technology was employed. In our study, we set up four treatments, i.e., without biochar and straw (B0S0); biochar only (B1S0); straw returning only (B0S1); and biochar and straw (B1S1). Our results demonstrate that soil organic matter (SOM), available nitrogen (AN), and available potassium (AK) were increased by 34.71%, 22.96%, and 61.68%, respectively, under the B1S1 treatment compared to the B0S0 treatment. In addition, microbial carbon (MBC), dissolved organic carbon (DOC), and particulate organic carbon (POC) were significantly increased with the B1S1 treatment, by 55.13%, 15.59%, and 125.46%, respectively. The results also show an enhancement in microbial diversity, the composition of microbial communities, and the degree of soil humification with the application of biochar and straw. Moreover, by comparing the differences in soil fertility, DOM components, and other indicators under different treatments, the combined treatments of biochar and straw had a more significant positive impact on paddy soil fertility compared to biochar. In conclusion, our study revealed the combination of straw incorporation and biochar application has significant impacts and is considered an effective approach to improving soil fertility.

Straw Addition Enhances Crop Yield, Soil Aggregation, and Soil Microorganisms in a 14-Year Wheat-Rice Rotation System in Central China.

Straw return utilizes waste resources to reduce the use of chemical fertilizers worldwide. However, information is still lacking on the relative impact of straw return on soil fertility, the nutrient composition of different soil aggregates, and soil microbial communities. Therefore, this study aimed to understand the effects of different management practices on the crop yield, soil fertility, and soil community composition in a 14-year wheat-rice rotation system. The treatments included a control (without fertilizer and straw addition), chemical fertilization (NPK), straw return without fertilizer (S), and straw addition with chemical fertilizer (NPKS). The results showed that NPKS improved the wheat and rice yield by 185.12% and 88.02%, respectively, compared to the CK treatment. Additionally, compared to the CK treatment, the N, P, and K contents of the wheat stem were increased by 39.02%, 125%, and 20.23% under the NPKS treatment. Compared to the CK treatment, SOM, TN, TP, AN, AP, AK, CEC, AFe, AMn, ACu, and AZn were increased by 49.12%, 32.62%, 35.06%, 22.89%, 129.36%, 48.34%, 13.40%, 133.95%, 58.98%, 18.26% and 33.33% under the NPKS treatment, respectively. Moreover, straw addition promoted the creation and stabilization of macro-aggregates in crop soils. The relative abundance of macro-aggregates (0.25-2 mm) increased from 37.49% to 52.97%. Straw addition was associated with a higher proportion of aromatic and carbonyl carbon groups in the soil, which, in turn, promoted the formation of macro-aggregates. Redundancy analysis showed that straw return significantly increased the microbial community diversity. These findings demonstrate that straw addition together with chemical fertilizer could increase the crop yield by improving soil fertility, soil aggregate stability, and the diversity of fungi.

Influences of tobacco straw return with lime on microbial community structure of tobacco-planting soil and tobacco leaf quality.

Soil amendment is an important strategy for improving soil quality and crop yield. From 2014 to 2019, we conducted a study to investigate the effects of tobacco straw return with lime on soil nutrients, soil microbial community structure, tobacco leaf yield, and quality in southern Anhui, China. A field experiment was conducted with four treatments: straw removed (CK), straw return (St), straw return with dolomite (St + D), and straw return with lime (St + L). Results showed that after 5 years of application, the St + L significantly increased the soil pH by 16.9%, and the contents of soil alkaline nitrogen (N) and available potassium (K) by 17.2% and 23.0%, respectively, compared with the CK. Moreover, the St + L significantly increased tobacco leaf yield (24.0%) and the appearance (9.1%) and sensory (5.9%) quality of flue-cured tobacco leaves. The addition of soil conditioners (straw, dolomite, and lime) increased both the total reads and effective sequences of soil microorganisms. Bacterial diversity was more sensitive to changes in the external environment compared to soil fungi. The application of soil amendments (lime and straw) promoted the growth of beneficial microorganisms in the soil. Additionally, bacterial species had greater competition and limited availability of resources for survival compared to fungi. The results showed that soil microorganisms were significantly influenced by the presence of AK, AN, and pH contents. These findings can provide an effective method for improving the quality of flue-cured tobacco leaves and guiding the amelioration of acidic soil in regions where tobacco-rice rotation is practiced.

Associations of daytime napping and nighttime sleep quality with depressive symptoms in older Chinese: the Guangzhou biobank cohort study.

BACKGROUND: Poor sleep quality has been linked to depression in older adults, but results of the association between daytime napping and depression remains limited and conflicting. Moreover, whether the association of daytime napping with depression varies by nighttime sleep quality is unclear. Hence, we examined the associations of daytime napping and nighttime sleep quality with depressive symptoms in older Chinese. METHODS: A total of 16,786 participants aged ≥50 from the Guangzhou Biobank Cohort Study second-round examination (2008-2012) were included in this cross-sectional study. Geriatric Depression Scale (GDS-15), Pittsburgh Sleep Quality Index (PSQI), napping and demographic data were collected by face-to-face interview using a computerized questionnaire. Logistic regression was used to calculate odds ratio (OR) of depressive symptoms for napping and sleep quality. RESULTS: The prevalence of depressive symptoms (GDS score > 5) and poor global sleep quality (PSQI score ≥ 6) was 5.3 and 31.9%, respectively. Compared to non-nappers, nappers showed significantly higher odds of depressive symptoms, with OR (95% confidence interval (CI)) being 1.28 (1.11-1.49). The odds of depressive symptoms for daytime napping varied by nighttime sleep quality (P for interaction = 0.04). In good-quality sleepers, compared to non-nappers, nappers had significantly higher odds of depressive symptoms, with OR (95% CI) being 1.57 (1.23-2.01), whereas no association was found in poor-quality sleepers (OR = 1.13, 0.94-1.36). CONCLUSION: Napping was associated with higher odds of depressive symptoms in older people, and the association was stronger in good-quality sleepers.

Parity and incident type 2 diabetes in older Chinese women: Guangzhou Biobank Cohort Study.

This study examined the association between parity and incident type 2 diabetes in older Chinese women and estimated the mediation effect of adiposity indicators. A total of 11,473 women without diabetes at baseline from 2003 to 2008 were followed up until 2012. We used Cox proportional hazards regression to assess the association between parity and incident type 2 diabetes, and mediation analysis to estimate the mediation effect of adiposity indicators. Compared to women with one parity, the hazard ratio (HR) (95% confidence interval (CI)) for incident type 2 diabetes was 0.85 (0.44-1.63), 1.20 (1.11-1.30), 1.28 (1.16-1.41) and 1.27 (1.14-1.42) for women with parity of 0, 2, 3, and ≥ 4, respectively. The proportion of indirect effect (95% CI) mediated by body mass index, waist circumference, hip circumference, waist-to-hip ratio, waist-to-height ratio and body fat percentage was 26.5% (19.2-52.2%), 54.5% (39.4-108.7%), 25.1% (18.2-49.1%), 35.9% (25.6-74.1%), 50.3% (36.5-98.6%) and 15.1% (- 66.4 to 112.3%), respectively. Compared to women with one parity, women with multiparity (≥ 2) had a higher risk of incident type 2 diabetes and up to half of the association was mediated by abdominal obesity.

Association of Salt Intake with Muscle Strength and Physical Performance in Middle-Aged to Older Chinese: The Guangzhou Biobank Cohort Study.

Older people have higher amounts of sodium accumulation in skeletal muscles than younger people, indicating the possible role of salt intake on muscular and physical function. This large population-based cross-sectional study examined the association of salt intake with muscle strength and physical performance in 4867 participants with an average age of 60.4 (standard deviation = 7.7) years. Information on salt intake was collected from self-reports. Absolute and relative grip strength (AGS and RGS), timed up-and-go test (TUGT), and falls were considered the indicators of muscle strength and physical performance. Linear and logistic regression were used to examine the associations of salt intake with AGS, RGS, TUGT score, and falls, adjusting for demographic and lifestyle factors, body mass index, self-rated health, and self-reported hypertension. Higher salt intake was independently associated with lower grip strength and a higher TUGT score. Versus light salt intake, the adjusted ß (95% confidence interval (CI)) of AGSmax, RGSmax, and TUGT scores in those with salty taste were -0.53 (-0.97, -0.08) kg, -0.04 (-0.06, -0.02) kg per kg/m2, and 0.08 (0.02, 0.14) s, respectively. A non-significant association was found between salt intake and falls. In sex-stratification analysis, the association remained in women but became non-significant in men. Our results suggest that avoiding high-salt diets may play a role in preserving muscle strength and physical function in the elderly, especially in women.

Obesity indicators as mediators of the association between age at menopause and blood pressure values.

Having a later age at menopause is associated with having a higher blood pressure (BP) value, but the mediation pathways remain unclear. We quantitatively examined the mediation effects of various obesity indicators using baseline data from phase 4 of the Guangzhou Biobank Cohort Study. The product of coefficients approach and bootstrapping procedures were used to assess the mediation effects of body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR) on the association between age at menopause and BP values. Age, education, occupation, family income, smoking, drinking, diet, physical activity, age at menarche, number of births, fasting glucose, triglycerides, and high-density lipoprotein cholesterol were adjusted as covariates. Of 5429 women with natural menopause, the mean age and menopausal age were 60.0 (standard deviation = 5.8) and 50.3 (3.1) years, respectively. The prevalence of hypertension was 29.6%. In women with a menopausal age of ≥50 years, BMI, WC, WHR and WHtR showed significant mediation effects on the positive association between menopausal age and BP. The adjusted proportion (95% confidence interval) of the mediation effects for those variables were 26.04% (10.40-116.82%), 25.92% (10.19-108.57%), 14.11% (3.59-62.78%), and 23.17% (8.70-95.81%), respectively, for systolic BP values and 22.59% (10.72-53.60%), 20.67% (9.83-49.31%), 9.21% (2.73-23.92%), and 17.19% (7.56-41.31%) for diastolic BP values. In women with a menopausal age of <50 years, no significant association between age at menopause and systolic/diastolic BP values was found. In conclusion, obesity indicators showed significant mediating effects on the association between having a later age at menopause and having a higher BP value. Further longitudinal studies with detailed and accurate measurements of metabolic changes after menopause and sufficient follow-up are warranted to confirm these results. We demonstrated obesity indicators showed significant mediating effects on the association between later age at menopause (≥50 years) and higher BP.

Association of sleep duration and napping with stroke mortality in older Chinese: A 14-year prospective cohort study of the Guangzhou Biobank Cohort study.

STUDY OBJECTIVE: Evidence regarding the association of short sleep duration and napping with stroke remains limited and controversial. We examined the association of sleep duration and napping with risk of stroke mortality in an older Chinese cohort. METHODS: Sleep duration and daytime napping were assessed by face-to-face interview during 2003-2008. Information of causes of death until April 30, 2021 was collected via record linkage with the Death Registry. Cox regression was used to calculate the hazard ratio (HR) and 95% confidence interval (CI). RESULTS: Of 27,254 participants aged average 62.0 (standard deviation = 7.1) years, 818 stroke deaths occurred within 388,798 person-years (mean = 14.3 years) of follow-up. A U-shaped relation between sleep duration and risk of stroke mortality was observed. Participants with short (≤5 h/day) or long sleep duration (≥9 h/day) showed higher risks of total stroke mortality, with adjusted HRs (95% CIs) being 1.27 (1.01-1.59) and 1.37 (1.07-1.75), respectively. However, non-significant association of short or long sleep duration with hemorrhagic or ischemic stroke mortality was found. The associations of short and long sleep duration with total stroke mortality were more pronounced in those with hypertension (P for interaction with hypertension = 0.01), with HRs (95% CIs) being 1.37 (1.04-1.82) and 1.77 (1.33-2.36), respectively. No association between napping and risk of stroke mortality was found. CONCLUSIONS: Both short and long sleep duration, but not daytime napping, were associated with higher risk of stroke mortality. Public health messages to encourage good sleep hygiene may be important, especially for people with hypertension.

Association of Hand Grip Strength with Mild Cognitive Impairment in Middle-Aged and Older People in Guangzhou Biobank Cohort Study.

Background: Lower hand grip strength has been linked to cognitive impairment, but studies in older Chinese are limited. We examined the association of hand grip strength with cognitive function in a large sample of older Chinese. Methods: 6806 participants aged 50+ years from the Guangzhou Biobank Cohort Study (GBCS) were included. Relative grip strength was calculated by absolute handgrip strength divided by the body mass index (BMI). Cognitive function was assessed using the Delayed Word Recall Test (DWRT, from 0 to 10) and the Mini Mental State Examination (MMSE, from 0 to 30), with higher scores indicating better cognition. Results: After adjusting for multiple potential confounders, lower absolute grip strength and relative grip strength were significantly associated with lower DWRT (all p < 0.05) in all participants. No significant interaction effects between sex and handgrip strength on cognitive impairment were found (p from 0.27 to 0.87). No significant association between handgrip strength and total MMSE scores was found in the total sample or by sex (p from 0.06 to 0.50). Regarding the individual components of MMSE, lower absolute and relative grip strength were significantly associated with lower scores of the recall memory performance in all participants (p from 0.003 to 0.04). Conclusion: We have shown for the first time a positive association of grip strength with recall memory performance, but not general cognitive function in older people, which warrants further investigation.

Low-Carbohydrate Diets and Mortality in Older Asian People: A 15-Year Follow-Up from a Prospective Cohort Study.

The long-term effects of a low-carbohydrate diet (LCD) on mortality, accounting for the quality and source of the carbohydrate, are unclear. Hence, we examined the associations of LCDs with all-cause and cause-specific mortality in a prospective cohort study. A total of 20,206 participants (13.8% diabetes) aged 50+ years were included. Overall, vegetable-based and meat-based LCD scores were calculated based on the percentage of energy as total and subtypes of carbohydrates, fat, and protein. Cox regression analysis was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs). During 294,848 person-years of follow-up, 4624 deaths occurred, including 3661 and 963 deaths in participants without and with diabetes, respectively. In all participants, overall LCD score was not associated with all-cause and cause-specific mortality, after multivariable adjustment. However, for the highest versus the lowest quartiles of vegetable-based LCD, the adjusted HRs (95%CIs) of all-cause and CVD mortality were 1.16 (1.05-1.27) and 1.39 (1.19-1.62), respectively. The corresponding values for highest versus lowest quartiles of meat-based LCD for all-cause and CVD mortality were 0.89 (0.81-0.97) and 0.81 (0.70-0.93), respectively. Similar associations were found in participants without diabetes. In patients with diabetes, the adjusted HR (95%CI) of CVD mortality for the highest versus the lowest quartiles of vegetable-based LCD was 1.54 (1.11-2.14). Although there were no significant associations with overall LCD score, we found that the vegetable-based LCD score was positively, whereas the meat-based LCD score was negatively, associated with all-cause and CVD mortality in older Asian people.

Mendelian randomization analysis of vitamin D in the secondary prevention of hypertensive-diabetic subjects: role of facilitating blood pressure control.

BACKGROUND: Vitamin D (Vit-D) promotes vascular repair and its deficiency is closely linked to the development of type 2 diabetes mellitus (T2DM) and hypertension. Whether genetially predicted vitamin D status (serological 25-hydroxyvitamin D [25(OH)D]) confers secondary protection against cardiovascular diseases (CVD) among high-risk hypertensive-diabetic subjects was unknown. METHODS: This is a prospective, individual-data, two-sample Mendelian randomization study. We interrogated 12 prior GWAS-detected SNPs of comprehensive Vit-D mechanistic pathways using high-throughput exome chip analyses in a derivation subcohort (n = 1460) and constructed a genetic risk score (GRS) (rs2060793, rs4588, rs7041; F-statistic = 32, P < 0.001) for causal inference of comprehensive CVD hard clinical endpoints in an independent sample of hypertensive subjects (n = 3746) with prevailing co-morbid T2DM (79%) and serological 25(OH)D deficiency [< 20 ng/mL] 45%. RESULTS: After 55.6 ± 28.9 months, 561 (15%) combined CVD events including myocardial infarction, unstable angina, ischemic stroke, congestive heart failure, peripheral vascular disease, and cardiovascular death had occurred. Kaplan-Meier analysis showed that genetically predicted reduced vitamin D status was associated with reduced event-free survival from combined CVD events (log-rank = 13.5, P = 0.001). Multivariate-adjusted per-allele increase in GRS predicted reduced combined CVD events (HR = 0.90 [0.84 to 0.96], P = 0.002). Mendelian randomization indicates that increased Vit-D exposure, leveraged through each 1 ng/mL genetically instrumented rise of serum Vit-D, protects against combined CVD events (Wald's estimate: OR = 0.86 [95%CI 0.75 to 0.95]), and myocardial infarction (OR = 0.76 [95%CI 0.60 to 0.90]). Furthermore, genetically predicted increase in Vit-D status ameliorates risk of deviation from achieving guideline-directed hypertension control (JNC-8: systolic target < 150 mmHg) (OR = 0.89 [95%CI 0.80 to 0.96]). CONCLUSIONS: Genetically predicted increase in Vit-D status [25(OH)D] may confer secondary protection against incident combined CVD events and myocardial infarction in a hypertensive-diabetic population where serological 25(OH)D deficiency is common, through facilitating blood pressure control.

Mendelian Randomization Focused Analysis of Vitamin D on the Secondary Prevention of Ischemic Stroke.

BACKGROUND AND PURPOSE: Experimental studies showed vitamin D (Vit-D) could promote vascular regeneration and repair. Prior randomized studies had focused mainly on primary prevention. Whether Vit-D protects against ischemic stroke and myocardial infarction recurrence among subjects with prior ischemic insults was unknown. Here, we dissected through Mendelian randomization any effect of Vit-D on the secondary prevention of recurrent ischemic stroke and myocardial infarction. METHODS: Based on a genetic risk score for Vit-D constructed from a derivation cohort sample (n=5331, 45% Vit-D deficient, 89% genotyped) via high-throughput exome-chip screening of 12 prior genome-wide association study-identified genetic variants of Vit-D mechanistic pathways (rs2060793, rs4588, and rs7041; F statistic, 73; P<0.001), we performed a focused analysis on prospective recurrence of myocardial infarction (MI) and ischemic stroke in an independent subsample with established ischemic disease (n=441, all with prior first ischemic event; follow-up duration, 41.6±14.3 years) under a 2-sample, individual-data, prospective Mendelian randomization approach. RESULTS: In the ischemic disease subsample, 11.1% (n=49/441) had developed recurrent ischemic stroke or MI and 13.3% (n=58/441) had developed recurrent or de novo ischemic stroke/MI. Kaplan-Meier analyses showed that genetic risk score predicted improved event-free survival from recurrent ischemic stroke or MI (log-rank, 13.0; P=0.001). Cox regression revealed that genetic risk score independently predicted reduced risk of recurrent ischemic stroke or MI combined (hazards ratio, 0.62 [95% CI, 0.48-0.81]; P<0.001), after adjusted for potential confounders. Mendelian randomization supported that Vit-D is causally protective against the primary end points of recurrent ischemic stroke or MI (Wald estimate: odds ratio, 0.55 [95% CI, 0.35-0.81]) and any recurrent or de novo ischemic stroke/MI (odds ratio, 0.64 [95% CI, 0.42-0.91]) and recurrent MI alone (odds ratio, 0.52 [95% CI, 0.30-0.81]). CONCLUSIONS: Genetically predicted lowering in Vit-D level is causal for the recurrence of ischemic vascular events in persons with prior ischemic stroke or MI.

Brain-derived neurotrophic factor gene variants and obesity in former smokers.

OBJECTIVE: From genome-wide association studies, brain-derived neurotrophic factor (BDNF) locus on chromosome 11 was the only SNP associated with both smoking and body mass index (BMI) in European, African and Asian population. This study aims to explore the unique genetic predisposition to obesity in former smokers by examining the effects of BDNF on BMI and waist circumference (WC). METHODS: The study design is case-control study with a cohort validation in supplementary. We included 15,072 ethnic Chinese participants in the Guangzhou Biobank Cohort Study (GBCS) with data of four BDNF SNPs related to both BMI and smoking behavior. We used baseline smoke exposure data in 2003-2007 and follow-up outcomes of general obesity (by BMI) and central obesity (WC) in 2008-2012. Odds ratios (ORs) and 95% confidence intervals (CIs) for general obesity and central obesity associated with these SNPs were derived from logistic regression. RESULTS: Of 15,072 participants (3169 men and 11,903 women), 1664 (11.0%) had general and 7868 (52.2%) had central obesity. In 1233 former smokers, the rs6265 GG, versus AA, genotype was associated with higher risks of general obesity (OR = 1.79, 95% CI = 1.06-3.01) and central obesity (OR = 2.08, 95% CI = 1.47-2.92) after adjustment. These associations were not significant in never or current smokers. In former heavy (≥20 cigarettes/day) smokers, the rs6265 GG genotype showed a higher odds for general obesity (OR = 2.15, 95% CI = 1.05-4.40), while no association was found in former light (1-9 cigarettes/day) smokers. Similar results were found for the association of rs6265 with central obesity and for the associations of other two BDNF SNPs (rs4923457 and rs11030104) with both general and central obesity. CONCLUSIONS: We firstly identified the genetic predisposition (BDNF SNPs) to general and central obesity in former smokers, particularly in former heavy smokers. The different associations of the SNPs for general/central obesity in different smoke exposure groups may be related to the competitive performance of the sites and epigenetic modification, which needs further study.

Natural menopausal age and cardiovascular disease risk factors in older Chinese women: Guangzhou Biobank Cohort Study.

OBJECTIVE: To examine the associations of natural menopausal age with cardiovascular disease risk factors and whether the associations varied by parity in older Chinese women. METHODS: Information of demographic characteristics, lifestyles, and reproductive factors was collected by face-to-face interview. Framingham Risk Score was used as an indicator of cardiovascular disease risk, with a score ≥ 10% considered as high cardiovascular disease risk (vs low, dichotomous). Multivariable logistic and linear regressions were used to examine the associations of menopausal age with cardiovascular disease risk factors. RESULTS: Of 18,339 women aged 50+ years, the average (standard deviation) age was 61.8 (6.9) years. Compared with women with menopausal age of 45 to 54 years, after adjustment for multiple potential confounders, women with menopausal age <45 years or ≥55 years had higher Framingham Risk Score (0.93%, 95% confidence interval: 0.40-1.46, and 0.69%, 95% confidence interval: 0.18-1.20, respectively). Women with menopausal age <45 or ≥55 years had higher odds of high cardiovascular disease risk (vs low) (odds ratio [95% confidence interval]:1.26 (1.10-1.44) and 1.17 (1.02-1.33), respectively). The associations of menopausal age with the Framingham Risk Score varied by parity (P for interaction ≤0.001). The Framingham Risk Score was higher in those with one to three parity (<45 y: 1.01 [0.43-1.59]; ≥55 y: 1.14 [0.60-1.68]) and lower for parity ≥4 (<45 y: -0.33 [-1.84 to 1.18]; ≥55 y: -2.02 [-3.82 to -0.22]). In nulliparous women, the Framingham Risk Score was highest in menopausal age <45 years (3.97 [1.67-6.26]), but the differences were nonsignificant in menopausal age ≥55 years (0.66 [-1.38 to 2.71]). CONCLUSIONS: Both early and late natural menopausal ages were associated with a higher cardiovascular disease risk, and the associations were stronger in those with lower parity.

Video Summary:http://links.lww.com/MENO/A813 .

Mortality in relation to changes in physical activity in middle-aged to older Chinese: An 8-year follow-up of the Guangzhou Biobank Cohort Study.

BACKGROUND: Physical activity (PA) is generally encouraged. Studies from developed countries in the West have shown that maintenance of adequate PA or increasing PA are associated with lower mortality risk. It is unclear whether these associations apply to an older Chinese population. Hence, we examined the changes in PA prospectively among a middle-aged and older Chinese population over an average of 4 years and explored their subsequent mortality risks. METHODS: Metabolic equivalent scores of PA among participants in the Guangzhou Biobank Cohort Study were calculated. Participants were divided into 3 groups related to PA level, and changes in PA were classified into 9 categories. Information on vital status and causes of death from March 2008 to December 2012 (the first repeated examination) until December 31, 2017, was obtained via record linkage with the Death Registry. RESULTS: Of 18,104 participants aged 61.21 ± 6.85 years (mean ± SD), 1461 deaths occurred within 141,417 person-years. Compared to participants who maintained moderate PA, those who decreased PA from moderate or high levels to a low level had increased risks for all-cause mortality (hazard ratio (HR) = 1.47, 95% confidence interval (95%CI): 1.11-1.96). Participants who maintained a high level of PA (HR = 0.83, 95%CI: 0.70-0.98) or increased PA from low to high levels (HR = 0.71, 95%CI: 0.52-0.97) showed lower all-cause mortality risks. Those who maintained low PA levels showed a higher all-cause mortality risk, whereas those who increased their PA levels showed a non-significantly lower risk. Similar results were found for cardiovascular disease risk. CONCLUSION: Even at an older age, maintaining a high PA level or increasing PA from low to high levels results in lower mortality risks, suggesting that substantial health benefits might be achieved by maintaining or increasing engagement in adequate levels of PA. The increased risk of maintaining a low PA level or decreasing PA to a low level warrants the attention of public health officials and clinicians.

Association of hepatitis B surface antigen seropositivity and hepatitis B surface antibody seropositivity with diabetes: a cross-sectional study based on two Chinese populations in Guangdong, China.

OBJECTIVES: To examine whether hepatitis B surface antigen (HBsAg) seropositivity and hepatitis B surface antibody (HBsAb) seropositivity were associated with the presence of diabetes in two population-based studies in southern China, the Guangzhou Biobank Cohort Study (GBCS) and the Major Infectious Disease Prevention and Control (MIDPC) study. DESIGN: A cross-sectional study. SETTING: The GBCS was conducted among a community social and welfare organisation with branches in all 10 districts of Guangzhou. The MIDPC was conducted among the community residents in two districts of Guangzhou and three districts of Zhongshan. PARTICIPANTS: 4947 participants from the GBCS and 4357 participants from the MIDPC were included in this study. PRIMARY AND SECONDARY OUTCOME MEASURES: Type 2 diabetes was the main study outcome, which was diagnosed by fasting blood glucose ≥7.0 mmol/L, and/or self-reported history of diabetes. RESULTS: After adjusting for age, sex, education, occupation, smoking status, alcohol use, physical activity and body mass index, we found no association of HBsAg seropositivity in GBCS or MIDPC (OR=1.12, 95% CI 0.74 to 1.69, and OR=0.83, 95% CI 0.59 to 1.17, respectively), and HBsAb seropositivity (OR=0.85, 95% CI 0.65 to 1.12, OR=1.00, 95% CI 0.86 to 1.16, respectively) with the presence of diabetes. Null associations were found for analysis pooling GBCS and MIDPC data after similar adjustment. The adjusted OR for the associations of HBsAg seropositivity and HBsAb seropositivity with the presence of diabetes in the pooled sample was 0.91 (95% CI 0.70 to 1.19) and 0.98 (95% CI 0.86 to 1.12), respectively. CONCLUSIONS: Taking advantage of data from two large cross-sectional studies, we found no association of serological status of HBsAg and HBsAb with the presence of diabetes or glucose measures.

Genetic scores for BMI related to metabolically unhealthy obesity in an older Chinese population.

OBJECTIVE: In this study, a genetic risk score (GRS) for the body mass index (BMI) tested and built using a large sample of Chinese individuals aged at least 50 years in southern China. We collected information regarding the participants' weights at 20 years of age and middle age and tested the BMI-GRS effect modes. METHODS: This study involved a prospective study design. The genetic data of the participants in from the Guangzhou Biobank Cohort Study and selected BMI-related single-nucleotide polymorphisms (SNPs) were used to establish the GRS. RESULTS: We included 13 597 participants with 12 SNPs. After adjusting for covariates, the high-GRS group was 36% (95% CI: 25%-48%) and 34% (95% CI: 23%-47%) more likely of being overweight at baseline and follow-up, respectively, and 56% (95% CI: 34%-82%) and 49% (95% CI: 29%-72%) more likely of being obese at baseline and follow-up, respectively, compared with the low-GRS group (P-value for all trends <.05). The RRs for the incidences of metabolically healthy and unhealthy obese (MHO and MUO, respectively) individuals in the high-GRS group were 0.94 (95% CI: 0.65-1.35) and 1.28 (95% CI: 1.00-1.63), respectively. CONCLUSION: High-GRS participants were more likely to be overweight/obese at baseline and follow-up, and this relationship exhibited a dose-response relationship. The GRS was also associated with MUO.

Root-zone fertilization improves crop yields and minimizes nitrogen loss in summer maize in China.

It is urgently to minimize nitrogen (N) loss while simultaneously ensuring high yield for maize in China. A two-year field experiment was conducted to determine the effects of root-zone fertilization (RZF) and split-surface broadcasting (SSB) on grain yield, N use efficiency (NUE), and urea-15N fate under different N rates (135, 180 and 225 kg ha-1). Results showed that RZF increased grain yield by 11.5%, and the N derived from fertilizer (Ndff%) by 13.1-19.6%, compared with SSB. The percentage of residual 15N in the 0-80 cm soil was 37.2-47.4% after harvest; most 15N (64.4-67.4%) was retained in the top 20 cm. RZF significantly increased the N apparent recovery efficiency (NARE) and 15N recovery in maize by 14.3-37.8% and 21.9-30.0%, respectively; while decreased N losses by 11.2-24.2%, compared with SSB. The RZF of urea can be considered a slow-release fertilizer, which better matches maize N demand and effectively reduces N losses. Overall, RZF achieved yields as high as the SSB, but with a 20-25% reduction in N application. These results help improve our understanding of N fate in the maize cropping system, and may help guide recommendations for N management in southeastern China.

One-time root-zone N fertilization increases maize yield, NUE and reduces soil N losses in lime concretion black soil.

Excess N-fertilizer application and inappropriate fertilization methods have led to low N use efficiency (NUE) and high N leaching. A field experiment was performed in a typical lime concretion black soil area to compare N application methods: split surface broadcasting (SSB) and one-time root-zone fertilization (RZF) on grain yield, NUE, the fate of 15N urea and soil N loss during the 2015 and 2016 maize growing seasons. Each application method was tested at N rates of 135 and 180 kg N ha-1, and a control (CK) with no N fertilizer. The RZF treatment remarkably increased grain yield by 7.0% compared with SSB treatment under 180 kg N ha-1, and significantly increased N derived from fertilizer by 28.5%. The residual 15N in the 0-80 cm soil layer was 40.6-47.6% after harvest, 61.8-70.9% of which was retained in 0-20 cm. The RZF remarkably increased the 15N recovery in maize by 28.7%, while significantly decreased the potential N losses by 30.2% compared with SSB in both seasons. In conclusion, one-time RZF of urea is recommended for obtaining high yields, increasing NUE, and minimizing N losses in maize, which deserves more attention for developing and applying in the future.

Age at menarche and depressive symptoms in older Southern Chinese women: A Mendelian randomization study in the Guangzhou Biobank Cohort Study.

To clarify the causal role of age at menarche in depressive symptoms we conducted a Mendelian randomization study using a large Southern Chinese cohort (n = 12,233). A genetic allele score was derived using stepwise regression with cross validation. Older age at menarche was not associated with geriatric depression scale score. Our findings suggest that higher rates of depression in women are likely attributable to other factors which require investigation.