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Results for “mediation analysis”

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PubMed1997

Rapid discrimination of Mycobacterium tuberculosis complex strains by ligation-mediated PCR fingerprint analysis.

A ligation-mediated PCR (LMPCR) method for the amplification of sequences flanking the IS6110 of the Mycobacterium tuberculosis complex has been developed. The method uses one primer specific for IS6110 and a second specific for a linker ligated to SalI-restricted genomic DNA. LMPCR is a rapid screening method, valuable for the fingerprinting of M. tuberculosis complex strains.

Bacterial Typing Techniques↗

PubMed2024

Mediating effects of BMI on the association between DNA methylation regions and 24-h blood pressure in African Americans.

BACKGROUND: DNA methylation is an important epigenetic mechanism that may influence blood pressure (BP) regulation and hypertension risk. Obesity, a major lifestyle factor associated with hypertension, may interact with DNA methylation to affect BP. However, the indirect effect of DNA methylation on 24-h BP measurements mediated by obesity-related phenotypes such as BMI has not been investigated. METHODS: Causal mediation analysis was applied to examine the mediating role of BMI in the relation between DNA methylation and 24-h BP phenotypes, including SBP, DBP and mean arterial blood pressure (MAP), in 281 African American participants. RESULTS: Analysis of 38 215 DNA methylation regions, derived from 1 549 368 CpG sites across the genome, identified up to 138 methylation regions that were significantly associated with 24-h BP measurements through BMI mediation. Among them, 38 (19.2%) methylation regions were concurrently associated with SBP, DBP and MAP. Genes associated with BMI-mediated methylation regions are potentially involved in various chronic diseases such as coronary artery disease and renal disease, which are often caused or exacerbated by hypertension. Notably, three genes ( CDH4 , NOTCH1 and COLGALT1 ) showed both direct associations with 24-h BP measurements and indirect associations through BMI after adjusting for age and sex covariates. CONCLUSION: Our findings suggest that DNA methylation may contribute to the regulation of 24-h BP in African Americans both directly and indirectly through BMI mediation.

Humans↗

PubMed2026

Fungal drivers of mycotoxin contamination in wheat: Early warning and plasma-based control.

Mycotoxin contamination in wheat is a major food safety concern; however, quantitative evidence linking fungal community signals, mycotoxin exceedance risk, and wheat quality traits in naturally contaminated wheat remains limited. In this study, wheat samples were collected from mycotoxin-prone monitoring sites under unusually rainy conditions in 2022 to explore early-warning indicators and post-harvest mitigation strategies. According to the National Food Safety Standard of China GB 2761-2017, aflatoxin B1 (AFB1), deoxynivalenol (DON), and zearalenone (ZEN) exceeded the maximum limits in 52.24, 47.76, and 23.88% of samples, respectively; 38.81% exceeded the reference EU threshold for T-2 toxin, and 46.27% showed co-contamination with at least two mycotoxins above their respective thresholds. Although Alternaria, Cladosporium, and Epicoccum dominated the fungal community, Fusarium abundance was significantly associated with DON contamination and Fusarium-damaged kernels (FDKs). Mediation analysis identified DON as a significant mediator linking Fusarium abundance to FDKs, accounting for 68.41% of the total effect. In addition, Fusarium abundance above 3.70% showed strong predictive performance for DON exceedance, with an area under the curve of 0.906, indicating its potential as an early-warning indicator. Culture-based assays confirmed the toxigenic potential of Aspergillus and Fusarium isolates under simulated temperature and moisture conditions. After optimization using a toxin-spiked wheat flour model, dielectric barrier discharge cold plasma degraded AFB1, DON, and ZEN by 29.30-35.68%, disrupted the morphology of toxigenic fungi, and did not significantly affect wheat quality. This study provides practical insights into mycotoxin risk warning and post-harvest mitigation in wheat.

Triticum↗

PubMed2006

Regional white matter and neuropsychological functioning across the adult lifespan.

BACKGROUND: The current study utilized magnetic resonance imaging (MRI) to more fully elucidate the relationship among age, regional white matter, and neuropsychological functioning. METHODS: One hundred ninety-nine neurologically healthy adults received MRI and standardized neuropsychological assessment. MR images were spatially normalized and segmented by tissue type; relative white matter values in each of the four cerebral lobes in each hemisphere were computed. Subjects were divided into Younger (ages 21-30), Middle (ages 31-54), and Older (ages 55-79) age groups. RESULTS: The Older group had significantly less overall relative white matter than the Middle group, who had significantly less overall relative white matter than the Younger participants (F (2, 193) = 5.42, p = 0.005). Differences in frontal lobe white matter were of largest magnitude, followed by temporal lobe (F (6, 579) = 3.32, p = 0.003). Age and frontal and temporal lobe white matter were primarily associated with performance on neuropsychological tests of executive functioning and memory. Mediational analysis suggested that frontal lobe white matter mediated the relationship between age and performance on tasks of executive functioning and memory. CONCLUSIONS: The results confirm age-associated decline in frontal and temporal white matter, and age-related cognitive decline in several domains. Decline in neuropsychological functioning is, in part, mediated by a relative age-related reduction in frontal white matter.

Adult↗

PubMed2006

Relationships among dog ownership and leisure-time walking in Western Canadian adults.

BACKGROUND: Dog ownership may be an effective tailored intervention among adults for promoting physical activity. This study examined the relationship between walking, physical activity levels, and potential psychological mediators between people who owned dogs and those who did not own dogs in the Capital Region District of Greater Victoria, British Columbia, Canada. Data were collected in September 2004; analyses were conducted in January 2005. METHODS: A random sample of men (n=177) and women (n=174) aged 20 to 80 years participated. Questionnaires were mailed out in 2004 to collect information about demographics, dog ownership, leisure-time walking, physical activity levels, and theory of planned behavior (TPB) constructs. RESULTS: The analyses revealed that dog owners spent more time in mild and moderate physical activities and walked an average of 300 minutes per week compared to non-dog owners who walked an average of 168 minutes per week. A mediator analysis suggests that dog obligation acts as a mediator between dog ownership and physical activity. Moreover, the theory of planned behavior constructs of intention and perceived behavioral control explained 13% of the variance in walking behavior with an additional 11% variance in walking behavior being explained by dog obligation. Regarding intention to walk, the TPB explained 46% of the variance in intention to walk with dog obligation adding an additional 1% variance. CONCLUSIONS: In this group of Canadians, those who owned a dog participated in more mild to moderate physical activity than those who did not. Acquiring a dog should be explored as an intervention to get people more physically active.

Adult↗

PubMed2026

Early life sugar rationing and ageing related diseases, biological ageing and mortality.

Early-life nutrition may influence lifelong ageing, yet human evidence is scarce. Using Britain's postwar sugar rationing as a natural experiment, we examine its long-term effects in 64,809 United Kingdom Biobank participants. Exposure to sugar rationing during the first 1,000 days of life is associated with a 9% lower incidence of hallmark-related disease, with a hazard ratio of 0.91 and a 95% confidence interval of 0.88-0.94, and a 19% lower risk of all-cause mortality, with a hazard ratio of 0.81 and a 95% confidence interval of 0.69-0.93. Mediation analysis indicates that the survival association is statistically mediated, by approximately 60%, through differences in incident hallmark-related disease. Rationed individuals show 1.0-1.2-year younger biological ages across multiple clocks and lower organ ages, particularly in the lung, heart, and liver. Proteomic profiling identifies 47 altered proteins, with enrichment of adenosine monophosphate-activated protein kinase and longevity pathways and suppression of mechanistic target of rapamycin signaling. These findings are consistent with international recommendations to limit free or added sugars from the World Health Organization, United States Dietary Guidelines, and American Heart Association, and may inform policy discussions related to sugar taxation and infant food and marketing policies under the United Nations 2030 Agenda.

Humans↗

PubMed2006

Gastrointestinal-focused panic attacks among Cambodian refugees: associated psychopathology, flashbacks, and catastrophic cognitions.

Among Cambodian refugees attending a psychiatric clinic, we assessed psychopathology associated with gastrointestinal panic (GIP), and investigated possible causal mechanisms, including "fear of fear" and GIP-associated flashbacks and catastrophic cognitions. GIP (n=46) patients had greater psychopathology (Clinician-Administered PTSD Scale [CAPS] and Symptom Checklist-90-R [SCL]) and "fear of fear" (Anxiety Sensitivity Index [ASI]) than did non-GIP patients (n=84). Logistic regression revealed that general psychopathology (SCL; odds ratio=4.1) and fear of anxiety-related sensations (ASI; odds ratio=2.4) predicted the presence of GIP. Among GIP patients, a hierarchical regression revealed that GIP-associated trauma recall and catastrophic cognitions explained variance in GIP severity beyond a measure of general psychopathology (SCL). A mediational analysis indicated that SCL's effect on GIP severity was mediated by GIP-associated flashbacks and catastrophic cognitions.

Adolescent↗

PubMed2005

Social tuning of automatic racial attitudes: the role of affiliative motivation.

Consistent with the affiliative social tuning hypothesis, this study showed that the desire to get along with another person shifted participants' automatic attitudes toward the ostensible attitudes of that person. In Experiment 1, the automatic racial attitudes of women but not men emulated those of an experimenter displaying race-egalitarian attitudes or attitudes neutral with respect to race. Mediational analysis revealed that the gender difference in social tuning was mediated by liking for the experimenter. In Experiment 2, the likability of the experimenter was manipulated. Individuals who interacted with a likable experimenter exhibited social tuning more so than did those who interacted with a rude experimenter. These findings suggest that affiliative motives may elicit malleability of automatic attitudes independent of manipulations of social group exemplars.

Adult↗

PubMed2022

Temporal associations between leukocytes DNA methylation and blood lipids: a longitudinal study.

BACKGROUND: The associations between blood lipids and DNA methylation have been investigated in epigenome-wide association studies mainly among European ancestry populations. Several studies have explored the direction of the association using cross-sectional data, while evidence of longitudinal data is still lacking. RESULTS: We tested the associations between peripheral blood leukocytes DNA methylation and four lipid measures from Illumina 450 K or EPIC arrays in 1084 participants from the Chinese National Twin Registry and replicated the result in 988 participants from the China Kadoorie Biobank. A total of 23 associations of 19 CpG sites were identified, with 4 CpG sites located in or adjacent to 3 genes (TMEM49, SNX5/SNORD17 and CCDC7) being novel. Among the validated associations, we conducted a cross-lagged analysis to explore the temporal sequence and found temporal associations of methylation levels of 2 CpG sites with triglyceride and 2 CpG sites with high-density lipoprotein-cholesterol (HDL-C) in all twins. In addition, methylation levels of cg11024682 located in SREBF1 at baseline were temporally associated with triglyceride at follow-up in only monozygotic twins. We then performed a mediation analysis with the longitudinal data and the result showed that the association between body mass index and HDL-C was partially mediated by the methylation level of cg06500161 (ABCG1), with a mediation proportion of 10.1%. CONCLUSIONS: Our study indicated that the DNA methylation levels of ABCG1, AKAP1 and SREBF1 may be involved in lipid metabolism and provided evidence for elucidating the regulatory mechanism of lipid homeostasis.

Humans↗

PubMed2024

Role of myeloid cells in mediating the effects of lipids on ulcerative colitis.

OBJECTIVE: To evaluate the causal relationship between lipids and ulcerative colitis (UC) through Mendelian Randomization (MR), and to further investigate the involvement of immune cells in mediating this process. METHODS: Utilizing summary statistics from genome-wide association studies (GWAS) of individuals with European ancestry, we analyzed the causal link between 179 lipid types and UC (2,569 UC cases and 453,779 controls) through Two-sample Mendelian randomization (2SMR) and Bayesian-weighted MR (BWMR). Based on this, a mediation screening of 731 immune cell phenotypes was conducted to identify exposure and mediator factors. Lastly, the role and proportion of immune cells in mediating the causal effects of lipids on UC were assessed via reverse MR (RMR) and two-step MR. RESULTS: The results of MR showed that there was a causal relationship between the six genetically predicted lipid types and UC (P <0.05), and the four immune cell phenotypes were identified as mediators of the association between lipids and UC. Notably, Phosphatidylcholine (PC) (16:0_0:0) served as the exposure factor, and myeloid cells CD11b on CD33+ HLA DR+ CD14dim acted as the mediator. Mediation analysis showed that CD11b on CD33+ HLA DR+ CD14dim had a mediation effect of -0.0205 between PC (16:0_0:0) and UC, with the mediation effect ratio at 15.38%. CONCLUSION: Our findings elucidate the causal effect of lipids on UC and identify the significant mediating role of myeloid cells CD11b on CD33+ HLA DR+ CD14dim in regulating UC through PC (16:0_0:0), offering new pathways and strategies for UC clinical treatment.

Humans↗

PubMed2006

National differences in predictors of suicide among young and elderly citizens: linking societal predictors to psychological factors.

Suicide is usually conceptualized as arising either because of social phenomena or individual dynamics. In this study, these approaches were combined by analyzing suicide rates of younger people aged 15-24 and elderly aged 65-74 from 54 nations using societal variables in conjunction with psychological measures of citizen characteristics as mediators. A mediated analysis showed that psychological citizen factors, like home satisfaction and happiness, mediated the impact of societal variables, like the sex ratio, in predicting suicide rates. We found different psychological and societal predictors for young and elderly suicides, with elderly suicide rates being much more predictable. An age-responsive Durkheimian framework focusing on the dynamics of social integration at different ages was used to interpret these results.

Adolescent↗

PubMed1997

Locus of control as a stress moderator and mediator in children of divorce.

This paper examined the stress moderator and mediator effects of four dimensions of perceived control in children of divorce. The dimensions of locus of control included internal control for positive events, internal control for negative events, unknown control for positive events, and unknown control for negative events. The sample consisted of 222 children between the ages of 8 and 12 whose parents had divorced in the previous 2 years. Moderational analyses showed that unknown control for positive events interacted with negative events to predict total symptoms. Plots of the simple slopes indicated a stress buffering effect whereby the slope of negative events on symptoms was higher for high than for low levels of unknown control for positive events. Mediational analysis showed that the relations between negative events and symptoms were mediated by both unknown control for positive events and unknown control for negative events. In contrast, evidence was not found for either a stress mediational or a moderational model for perceived internal control for positive or negative events. These results suggest that unknown control beliefs may be a particularly important dimension of control for children of divorce.

Adaptation, Psychological↗

PubMed2005

Mood-congruent cognitions constitute mood experience.

Three studies tested the assumption of a dispositional theory of moods that mood-related cognitions constitute essential parts of the phenomenal mood experience. In Study 1, after a hot- versus a cold-, sad-, or angry-mood induction, participants reported their momentary moods and their momentary mood-related cognitions. Self-reported moods and mood-related cognitions changed in a strictly parallel fashion in all mood induction groups. A mediation analysis showed that the influences of distraction on moods were completely mediated by changes in mood-related cognitions. Study 2 replicated the central findings of Study 1 with a musical mood induction procedure. Study 3 showed that the findings do not depend on the explicit manipulation of moods. The results support the tested assumption.

Adult↗

PubMed2025

Role of HLA-DRA-CREB3L4 regulatory axis in the pathogenesis of ovarian endometriosis: Inhibition of CREB3L4 expression by HLA-DRA increases the risk of disease.

BACKGROUND: Ovarian endometriosis is a common gynecological condition characterized by the abnormal growth of endometrial-like tissue in locations outside the uterus, and its development remains poorly understood. This study aims to investigate potential protein regulatory networks and assess their impact on disease risk using both protein quantitative trait locus (pQTL) analysis and Mendelian randomization (MR) techniques. METHODS: This study systematically integrates two major genome-wide pQTL databases, UKB-PPP and deCODE, to identify pQTL signals associated with ovarian endometriosis. Additionally, we utilized the GEO database to validate differences in protein expression. We conducted a Mendelian randomization analysis to further explore the regulatory relationships between proteins and their roles in disease development. RESULTS: After the Bonferroni correction, we identified 33 pQTL signals from UKB-PPP and 19 pQTL signals from deCODE. Among these, 8 signals from UKB-PPP and 3 signals from deCODE were validated based on expression differences. The mediation analysis results indicate that HLA-DRA significantly increases the risk of developing ovarian endometriosis by inhibiting the expression of CREB3L4 (with a mediation proportion of 13.99 %), and the direction of the mediation effect is consistent with the total effect. CONCLUSION: This study provides new insights that HLA-DRA downregulates the expression of CREB3L4, which may affect the risk of developing endometriosis. The results provide new evidence for understanding the genetic and molecular basis of ovarian endometriosis and establish a theoretical foundation for the development of future diagnostic markers and targeted treatment strategies.

Humans↗

PubMed1978

Use of a radioactive double labeling technique in the chemical analysis of the mediators of cellular immunity.

Radioactive double labeling was adapted for the analysis of mediators of cellular immunity. Two identical lymphocyte cultures were simultaneously labeled with [3H]- or [14C]leucine. Each of the cultures was stimulated with antigen or mitogen. The combined supernatants were then subjected to various fractionation procedures. By determining the isotope ratio in each fraction it is possible to identify those products of activated lymphocytes that have been produced either de novo or in increased amounts. The method proved sensitive enough to detect lymphocyte activation products in supernatants of activated lymphocyte cultures from guinea pig, mouse, and man.

Animals↗

PubMedDate not supplied

Depression-related hyperglycemia in type 1 diabetes: a mediational approach.

OBJECTIVE: Depression is linked with hyperglycemia and with an increased risk for diabetes complications, but the mechanisms underlying these relationships have not been established. In this study, we applied mediational analysis methods to determine whether the hyperglycemic effect of depression could be mediated by poor diabetes self-care. METHODS: Depression symptoms and diabetes self-care activity were assessed in a primary care sample of 188 patients with type 1 diabetes by using the Hopkins Symptom Checklist-90 (SCL-90) and the Summary of Diabetes Self-Care Activities (SDSCA). A composite score of self-care activity was formed from SDSCA ratings for diet amount, exercise, and glucose testing. Degree of hyperglycemia (level of glycosylated hemoglobin [HbA1c]), weight, insulin dose, and other clinical characteristics were obtained from electronic medical records. Ordinary least-squares regression was used to determine the effect of depression on HbA1c level controlling for weight and insulin dose. The SDSCA score was then added to the regression model to determine whether it attenuated the effect of depression symptoms on HbA1c level, thus providing suggestive evidence of mediation from these cross-sectional data. RESULTS: Depression symptoms, poor diabetes self-care, and hyperglycemia were correlated with one another in univariate analyses (p <.05). Depression symptoms were associated with higher HbA1c after controlling for weight and insulin dose (parameter estimate for depression 0.53, t = 3.6, p <.001). Inclusion of SDSCA in the model minimally attenuated the effect of depression symptoms (adjusted parameter estimate for depression 0.50, t = 3.3, p = .001). CONCLUSIONS: These findings do not support mediation of the depression-hyperglycemia relationship by diabetes self-care behavior. Other pathways, including psychophysiological mechanisms, should be investigated.

Adult↗

PubMed2026

Parenting styles and fertility intention: Mediating effects of childbearing beliefs and psychological resilience.

China's declining fertility rate is partly due to low fertility intention among childbearing population. To understand family influence on young people's fertility intention and its underlying mechanisms, this study examines how parenting styles (authoritarian vs. permissive) affect Chinese college students' fertility intention, with traditional childbearing beliefs and resilience as mediators. Data were collected from 839 participants (Age: M = 21.1, SD = 1.7 years) using structured questionnaires. Logistic regression found that a positive correlation between permissive parenting style and fertility intention, with authoritarian parenting having no impact. Mediation analysis showed the association between permissive parenting style and fertility intention was fully mediated through resilience ( = 0.0, 95%CI = [0.0,0.1]) and greater childbearing beliefs ( = 0.0, 95%CI = [0.0,0.1]). The findings indicate that permissive parenting is related to higher fertility intention in youth via resilience and childbearing beliefs. Promoting positive family environments and permissive parenting may enhance childbearing intention.

Humans↗

PubMedDate not supplied

Mediating factors for the long-term effects of parental alcoholism in women: the contribution of other childhood stresses and resources.

The primary aim of this study was to identify the stresses and resources in childhood that mediate the relationship between parental alcoholism and adult outcomes in women. Adult outcomes included alcohol problems and measures of psychosocial adjustment. Standardized measures and a face-to-face interview were used to collect data on 290 community-dwelling women, with siblings as collateral informants. Mediation analysis showed that the effect of parental alcoholism on several adult outcomes was indirect, mediated by the other stresses and resources examined. Contextual models such as those presented here are helpful in understanding the long-term effects of childhood environment on women.

Adult↗