Genomic differences between the new Fusarium oxysporum f. sp. apii (Foa) race 4 on celery, the less virulent Foa races 2 and 3, and the avirulent on celery f. sp. coriandrii.

BACKGROUND: Members of the F. oxysporium species complex (FOSC) in the f. sp. apii (Foa) are pathogenic on celery and those in f. sp. coriandrii (Foci) are pathogenic on coriander (=cilantro). Foci was first reported in California in 2005; a new and highly aggressive race 4 of Foa was observed in 2013 in California. Preliminary evidence indicated that Foa can also cause disease on coriander, albeit are less virulent than Foci. Comparative genomics was used to investigate the evolutionary relationships between Foa race 4, Foa race 3, and the Foci, which are all in FOSC Clade 2, and Foa race 2, which is in FOSC Clade 3. RESULTS: A phylogenetic analysis of 2718 single-copy conserved genes and mitochondrial DNA sequence indicated that Foa races 3 and 4 and the Foci are monophyletic within FOSC Clade 2; these strains also are in a single somatic compatibility group. However, in the accessory genomes, the Foci versus Foa races 3 and 4 differ in multiple contigs. Based on significantly increased expression of Foa race 4 genes in planta vs. in vitro, we identified 23 putative effectors and 13 possible pathogenicity factors. PCR primers for diagnosis of either Foa race 2 or 4 and the Foci were identified. Finally, mixtures of conidia that were pre-stained with different fluorochromes indicated that Foa race 4 formed conidial anastomosis tubes (CATs) with Foci. Foa race 4 and Foa race 2, which are in different somatic compatibility groups, did not form CATs with each other. CONCLUSIONS: There was no evidence that Foa race 2 was involved in the recent evolution of Foa race 4; Foa race 2 and 4 are CAT-incompatible. Although Foa races 3 and 4 and the Foci are closely related, there is no evidence that either Foci contributed to the evolution of Foa race 4, or that Foa race 4 was the recent recipient of a multi-gene chromosomal segment from another strain. However, horizontal chromosome transfer could account for the major difference in the accessory genomes of Foa race 4 and the Foci and for their differences in host range.

Peer Texting to Promote Quitline Use and Smoking Cessation Among Rural Participants in Vietnam: Randomized Clinical Trial.

Objectives: We tested an adapted version of an effective U.S.-based peer-texting intervention to promote Quitline use and smoking cessation among rural participants in Vietnam. Methods: We conducted a two-arm randomized trial with participants recruited at four rural community centers. The intervention included peer messages sent for six months that promoted Quitline use and smoking cessation. Additionally, biweekly two-way text messages assessed participants' interest in Quitline referral and current smoking status. Comparison participants received only the bi-weekly text message assessment of their current smoking status. At six months, we assessed Quitline use and smoking cessation. Smoking cessation was assessed using the 7-day point prevalence question and verified with a carbon monoxide breath monitor (<=6 ppm). Results: Among 750 participants, the intervention had higher Quitline verified use (18%, 95% CI 0.14, 0.22) than comparison (1%, 95% CI .2, 2, p < 0.0001). Carbon-monoxide-verified smoking cessation did not differ between the two groups. However, intervention (28.3%, 95% CI) and comparison (28.1%, 95% CI) participants had substantial rates of carbon monoxide cessation at 6 months (both 28%). Conclusion: Our study highlighted the promise of texting interventions to extend tobacco control efforts in Vietnam.

Brief report: airways abnormalities and rheumatoid arthritis-related autoantibodies in subjects without arthritis: early injury or initiating site of autoimmunity?

OBJECTIVE: To evaluate the presence of pulmonary abnormalities in rheumatoid arthritis (RA)-related autoantibody-positive subjects without inflammatory arthritis. METHODS: Forty-two subjects who did not have inflammatory arthritis but were positive for anti-cyclic citrullinated peptide antibodies and/or ≥2 rheumatoid factor isotypes (a profile that is 96% specific for RA), 15 autoantibody-negative controls, and 12 patients with established seropositive early RA (<1-year duration) underwent spirometry and high-resolution computed tomography (HRCT) lung imaging. RESULTS: The median age of autoantibody-positive subjects was 54 years, 52% were female, and 38% were ever-smokers; these characteristics were not significantly different from those of autoantibody-negative control subjects. No autoantibody-positive subject had inflammatory arthritis based on joint examination. HRCT revealed that 76% of autoantibody-positive subjects had airways abnormalities including bronchial wall thickening, bronchiectasis, centrilobular opacities, and air trapping, compared with 33% of autoantibody-negative controls (P = 0.005). The prevalence and type of lung abnormalities among autoantibody-positive subjects were similar to those among patients with early RA. In 2 autoantibody-positive subjects with airways disease, inflammatory arthritis classifiable as articular RA developed ∼13 months after the lung evaluation. CONCLUSION: Airways abnormalities that are consistent with inflammation are common in autoantibody-positive subjects without inflammatory arthritis and are similar to airways abnormalities seen in patients with early RA. These findings suggest that the lung may be an early site of autoimmune-related injury and potentially a site of generation of RA-related autoimmunity. Further studies are needed to define the mechanistic role of lung inflammation in the development of RA.

Structural and mechanistic insights into the inhibition of respiratory syncytial virus polymerase by a non-nucleoside inhibitor.

The respiratory syncytial virus polymerase complex, consisting of the polymerase (L) and phosphoprotein (P), catalyzes nucleotide polymerization, cap addition, and cap methylation via the RNA dependent RNA polymerase, capping, and Methyltransferase domains on L. Several nucleoside and non-nucleoside inhibitors have been reported to inhibit this polymerase complex, but the structural details of the exact inhibitor-polymerase interactions have been lacking. Here, we report a non-nucleoside inhibitor JNJ-8003 with sub-nanomolar inhibition potency in both antiviral and polymerase assays. Our 2.9 Å resolution cryo-EM structure revealed that JNJ-8003 binds to an induced-fit pocket on the capping domain, with multiple interactions consistent with its tight binding and resistance mutation profile. The minigenome and gel-based de novo RNA synthesis and primer extension assays demonstrated that JNJ-8003 inhibited nucleotide polymerization at the early stages of RNA transcription and replication. Our results support that JNJ-8003 binding modulates a functional interplay between the capping and RdRp domains, and this molecular insight could accelerate the design of broad-spectrum antiviral drugs.

Regiospecific O → N Acyl Migration as a Methodology to Access l-Altropyranosides with an N2,N4-Differentiation.

Pseudaminic acid and its biosynthetic altropyranoside precursors are bacterial components currently being investigated toward novel antibacterial strategies. One structural feature associated with these naturally occurring flagellar carbohydrates is the different N-acylation patterns on the two amido functionalities, posing a synthetic challenge. A new one-pot methodology is reported and a scope of diverse N2/N4-differentiated analogs are presented via a Staudinger reduction-mediated regiospecific O3 → N4 acyl migration, followed by an autonomous N2-acylation.

Tobacco smoking and nicotine dependence among patients with respiratory diseases in Vietnam: Status and correlated factors.

INTRODUCTION: Understanding nicotine dependence can support clinicians in enhancing the effectiveness of treatments for respiratory patients. Our research aimed to assess the severity of nicotine dependence among patients with respiratory diseases in Vietnam and accordingly suggest potential interventions for tobacco cessation. METHODS: A cross-sectional study was conducted at the Respiratory center of Bach Mai Hospital, Hanoi, for two months of 2016 (October and November). A total of 508 respondents participated in the study Data on socio-economic characteristics and smoking patterns were collected. The Euroqol-5 dimensions-5 levels (EQ-5D-5L) and Fagerström test for nicotine dependence (FTND) were used to evaluate patient's quality of life and the nicotine dependence level, respectively. Kruskal-Wallis and Chi-square tests were used to assess the differences between variables. We applied the multivariate logistic regression and Tobit regression to categorize the association between nicotine dependence level and other factors. RESULTS: A total of 508 patients enrolled in our study. Former smokers and current smokers accounted for 8.1% and 38.6% of the sample, respectively. Current smokers were more likely to be male, work as free lancers, and report anxiety/depression. Higher level of nicotine dependence among current smokers was associated with the employment status of the patient. The mean number of cigarettes per day was 15.7 (SD = 11.1). The mean score of the FTND was 5.1 (SD = 2.0). Freelancers were more likely to be a current smoker (OR = 2.65, 95% CI = 2.21; 5.79). People who experienced anxiety/depression had a higher likelihood of smoking (OR = 2.21, 95% CI = 1.04; 4.72). CONCLUSIONS: Current smokers demonstrated a moderate level of nicotine dependence, which predict a difficult quitting and suggest the development of specialized programs to support smoking cessation counseling. Furthermore, the capabilities of physicians in supporting and counseling patients in quitting smoking should be strengthened.

High Levels of Interferon-Alpha Expressing Macrophages in Human Breast Milk During SARS-CoV-2 Infection: A Case Report.

Introduction: In addition to hand washing and wearing masks, social distancing and reducing exposure time to <15 minutes are the most effective measures against the spread of COVID-19. Unfortunately, three of these guidelines are very difficult, if not impossible, for nursing babies: they cannot wear masks, stay six feet away from the lactating breasts, nor consistently finish within 15 minutes while nursing. We report a case of a nursing mother with SARS-CoV-2 infection, documenting changes of immune cells and cytokines in breast milk with and without the infection. Case Description: With Institutional Review Board (IRB) approval, we obtained expressed breast milk samples from a lactating mother before and during SARS-CoV-2 infection as documented by reverse transcription-PCR. Using flow cytometry analysis, we measured the immune cell profiles and expression of cytokines such as interferon alpha (IFNα) in milk leukocytes before and during infection. Results: There was an eightfold increase in IFNα+ milk leukocytes, from 1% before SARS-CoV-2 infection to 8% when actively infected. The milk macrophages showed the highest increase in IFNα expression. Both T and B lymphocytes showed mild increase. Innate lymphoid cells, neutrophils, and natural killer cells showed no increase in IFNα expression and the dendritic cells actually showed a reduction. Conclusion: We document the presence and high expression of IFNα in the breast milk macrophages of a lactating mother with confirmed COVID-19, compared with her milk before the infection.

Clinical characteristics and risk factors of gastroesophageal reflux disease in Vietnamese patients with upper gastrointestinal symptoms undergoing esophagogastroduodenoscopy.

BACKGROUND AND AIM: The risk factors associated with the increase in prevalence of gastroesophageal reflux disease (GERD) are not consistent across countries and there have been few studies in Asia in the past 10 years. This study was conducted to assess the features and risk factors of GERD in Vietnamese patients. METHODS: A cross-sectional study was conducted on 1947 out-patients ≥18 years of age who were presented with upper gastrointestinal symptoms and underwent esophagogastroduodenoscopy. Reflux esophagitis was graded according to the Los Angeles classification. Endoscopically suspected Barrett's esophagus (BE) was recorded according to the Prague C and M criteria and biopsy was taken for histologic examination. RESULTS: There were 511 (26.2%) patients with GERD, 242 (47.4%) with nonerosive reflux disease, and 269 (52.6%) with reflux esophagitis and/or BE. Epigastric pain, regurgitation, and heartburn were the chief complaints in 36.8%, 27.0%, and 9.2% of patients, respectively. Most of the patients with mucosal injury had reflux esophagitis in mild grade and BE in the form of C0M ≤2 (99.6%, 231/232 and 97.8%, 46/47, respectively). In multivariate analysis, hiatal hernia, male gender, waist-to-hip ratio (independent from general obesity), and smoking were risk factors for GERD while Helicobacter pylori infection was negatively associated with GERD. CONCLUSIONS: The majority of GERD patients had none or mild mucosal injury. Typical reflux symptoms, however, may not be the chief complaints. Central obesity would be more important than general obesity as a risk factor, while H. pylori infection was a "protective" factor for GERD in Vietnamese patients.

mHealth Messaging to Motivate Quitline Use and Quitting: Protocol for a Community-Based Randomized Controlled Trial in Rural Vietnam.

BACKGROUND: Tobacco kills more than 8 million people each year, mostly in low- and middle-income countries. In Vietnam, 1 in every 2 male adults smokes tobacco. Vietnam has set up telephone Quitline counseling that is available to all smokers, but it is underused. We previously developed an automated and effective motivational text messaging system to support smoking cessation among US smokers. OBJECTIVE: The aim of this study is to adapt the aforementioned system for rural Vietnamese smokers to promote cessation of tobacco use, both directly and by increasing the use of telephone Quitline counseling services and nicotine replacement therapy. Moreover, we seek to enhance research and health service capacity in Vietnam. METHODS: We are testing the effectiveness of our culturally adapted motivational text messaging system by using a community-based randomized controlled trial design (N=600). Participants were randomly allocated to the intervention (regular motivational and assessment text messages) or control condition (assessment text messages only) for a period of 6 months. Trial recruitment took place in four communes in the Hung Yen province in the Red River Delta region of Vietnam. Recruitment events were advertised to the local community, facilitated by community health workers, and occurred in the commune health center. We are assessing the impact of the texting system on 6-month self-reported and biochemically verified smoking cessation, as well as smoking self-efficacy, uptake of the Quitline, and use of nicotine replacement therapy. In addition to conducting the trial, the research team also provided ongoing training and consultation with the Quitline during the study period. RESULTS: Site preparation, staff training, intervention adaptation, participant recruitment, and baseline data collection were completed. The study was funded in August 2017; it was reviewed and approved by the University of Massachusetts Medical School Institutional Review Board in 2017. Recruitment began in November 2018. A total of 750 participants were recruited from four communes, and 700 (93.3%) participants completed follow-up by March 2021. An analysis of the trial results is in progress; results are expected to be published in late 2022. CONCLUSIONS: This study examines the effectiveness of mobile health interventions for smoking in rural areas in low- and middle-income countries, which can be implemented nationwide if proven effective. In addition, it also facilitates significant collaboration and capacity building among a variety of international partners, including researchers, policy makers, Quitline counselors, and community health workers. TRIAL REGISTRATION: ClinicalTrials.gov NCT03567993; https://clinicaltrials.gov/ct2/show/NCT03567993. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/30947.

Factors Affecting the Composition of Expressed Fresh Human Milk.

Breast milk is considered the ideal and preferred feeding for all infants through the first 4-6 months of life. It provides many short and long-term benefits to the infant and mother. In the absence of breastfeeding, expressed breast milk is the best way to provide nutrition. In the United States, the majority of breastfeeding mothers express milk at some point during the course of lactation. Breast milk is a dynamic fluid and its content changes with duration of lactation and varies between and among women. Many factors such as maternal diet and medications affect the constituents of breast milk. In addition, method of breast milk expression, handling, and storage can also influence its contents.

Iodine-mediated formal [3 + 2] annulation for synthesis of furocoumarin from oxime esters.

A novel synthesis of furocoumarins was developed by a reaction between oxime esters and 4-hydroxycoumarins. The reaction was proposed to undergo radical mechanism mediated by iodine, a cheap and common laboratory reagent. Mechanistic studies showed the key for the successful transformation was the presence of α-iodoimine intermediate which facilitated the ring-closing step. The developed conditions produced good functional group tolerance with a wide range of high-profile furocoumarin product. The potential for this strategy to be applied in other syntheses of heterocyclic compounds is highly achievable.

Prevalence, clinical characteristics, and risk factors of Barrett esophagus in Vietnamese patients with upper gastrointestinal symptoms.

The current barrier for investigation of Barrett esophagus (BE) in Asia is diagnostic standardization, which is a challenge to identify its true risk factors. This study aimed to investigate the prevalence, clinical characteristics and risk factors of BE in Vietnamese patients with upper gastrointestinal symptoms.A cross-sectional study was conducted on consecutive outpatients who underwent upper gastrointestinal endoscopy. Endoscopically suspected esophageal metaplasia (ESEM) which was clearly visible at least 1 cm above the gastroesophageal junction at endoscopy was taken biopsy. At least 1 biopsy per 2 cm in tongues of ESEM and 4 biopsies per 2 cm of circumferential ESEM were taken. The diagnostic criterion for BE was replacement of the normal squamous epithelial lining by columnar epithelium confirmed by histology.A total of 1947 patients were recruited. Forty-seven out of 58 patients with ESEM were histologically confirmed BE. The prevalences of BE and hiatal hernia (HH) were 2.4% (95% confidence interval [CI], 1.7-3.1%) and 2.3% (95% CI, 1.6-2.9%), respectively. Heartburn and/or regurgitation presented in only 61.7% (95% CI, 46.4-75.5%) of patients with BE. In multivariate analysis, the only 2 factors significantly associated with BE were HH (OR 7.53; 95% CI, 3.13-18.11; P < .001) and typical reflux symptom (OR 2.07; 95% CI, 1.12-3.83; P = .020).BE is not uncommon in Vietnamese patients with upper gastrointestinal symptoms. In addition, typical reflux symptoms and HH are the risk factors for BE in Vietnamese.

Effects of Different Comorbidities on Health-Related Quality of Life among Respiratory Patients in Vietnam.

Comorbidities are common in respiratory disease patients and have been well-known to impact their quality of life. The objective of this study is to estimate the minimal clinically important difference (MCID) of the health-related quality of life (HRQOL) among respiratory disease patients with different comorbidities in a Vietnamese tertiary hospital. We performed a cross-sectional study from October to November 2016 at the Respiratory Center of Bach Mai Hospital, Hanoi, with a total of 508 participants. Information about socio-economic characteristics, HRQOL and comorbidities of participants was collected. ANOVA was used to identify MCID between patients with and without specific comorbid conditions. Tobit regression was used to explore the associations between comorbidities and the HRQOL. Results showed that the prevalence of cardiovascular comorbidities was 23.8%, followed by musculoskeletal diseases (12.0%), digestive diseases (11.8%), endocrine diseases (10.0%), kidney diseases (5.1%) and ear, nose, and throat diseases (4.5%). Regarding HRQOL, having a problem in pain/discomfort was observed in 61.0% of participants, followed by anxiety/depression (48.2%). Mean EQ-5D index was 0.66 (SD (Standard Deviation) = 0.31). The significant MCID (p < 0.05) was found between patients with and without cardiovascular diseases, musculoskeletal diseases, kidney diseases, and endocrine diseases. The multivariate regression model showed that only musculoskeletal diseases were found to be related with the marked decrement of EQ-5D index score (Coef. = -0.13; 95% CI (Confident Interval) = -0.23; -0.02). Suffering at least one chronic illness was correlated to the marked decrease of EQ-5D index score (Coef. = -0.09; 95%CI = -0.17; -0.01). These results underline the importance of appropriate pain management as well as the provision of an interprofessional care approach to patients in order to alleviate the burden of comorbidities to their treatment outcomes and HRQOL.

Impact of a Smoking Cessation Quitline in Vietnam: Evidence Base and Future Directions.

Smoking is considered the most critical modifiable factor with regard to lung cancer and remains a public health concern in many countries, including Vietnam, which is among those countries with the highest tobacco consumption rates in the world. This study has examined the impact of national telephone counselling for smoking cessation and has identified the factors associated with the impact of the quitline among male callers in Vietnam. A randomized cross-sectional survey of 469 smokers who sought smoking cessation services via the national quitline was performed from September 2015 to May 2016. The primary outcomes were measured by a self-reported quit rate at the time of assessment, 7 day point prevalence abstinence (PA), 6 month prolonged PA, service satisfaction, and level of motivation. Among the participants, 31.6% were abstinent, and 5.1% of participants successfully stopped smoking and did not need to seek quitline support. Most of the clients were satisfied with the quality of service (88.5%), felt more confident about quitting (74.3%), and took early action via their first quit attempt (81.7%); 18.3% reported a more than 7 day abstinence period at the time of survey. The primary reasons for smoking relapse were surrounding smoking environments (51.6%) and craving symptoms (44.1%). Future smoking cessation efforts should focus on improving the quality of quitline services, client satisfaction, and developing a tailored program and counseling targeting smokers with specific characteristics, especially ones experiencing chronic diseases.

Which eHealth interventions are most effective for smoking cessation? A systematic review.

PURPOSE: To synthesize evidence of the effects and potential effect modifiers of different electronic health (eHealth) interventions to help people quit smoking. METHODS: Four databases (MEDLINE, PsycINFO, Embase, and The Cochrane Library) were searched in March 2017 using terms that included "smoking cessation", "eHealth/mHealth" and "electronic technology" to find relevant studies. Meta-analysis and meta-regression analyses were performed using Mantel-Haenszel test for fixed-effect risk ratio (RR) and restricted maximum-likelihood technique, respectively. Protocol Registration Number: CRD42017072560. RESULTS: The review included 108 studies and 110,372 participants. Compared to nonactive control groups (eg, usual care), smoking cessation interventions using web-based and mobile health (mHealth) platform resulted in significantly greater smoking abstinence, RR 2.03 (95% CI 1.7-2.03), and RR 1.71 (95% CI 1.35-2.16), respectively. Similarly, smoking cessation trials using tailored text messages (RR 1.80, 95% CI 1.54-2.10) and web-based information and conjunctive nicotine replacement therapy (RR 1.29, 95% CI 1.17-1.43) may also increase cessation. In contrast, little or no benefit for smoking abstinence was found for computer-assisted interventions (RR 1.31, 95% CI 1.11-1.53). The magnitude of effect sizes from mHealth smoking cessation interventions was likely to be greater if the trial was conducted in the USA or Europe and when the intervention included individually tailored text messages. In contrast, high frequency of texts (daily) was less effective than weekly texts. CONCLUSIONS: There was consistent evidence that web-based and mHealth smoking cessation interventions may increase abstinence moderately. Methodologic quality of trials and the intervention characteristics (tailored vs untailored) are critical effect modifiers among eHealth smoking cessation interventions, especially for web-based and text messaging trials. Future smoking cessation intervention should take advantages of web-based and mHealth engagement to improve prolonged abstinence.

Development of an edema factor-mediated cAMP-induction bioassay for detecting antibody-mediated neutralization of anthrax protective antigen.

Intoxication of mammalian cells by Bacillus anthracis requires the coordinate activity of three distinct bacterial proteins: protective antigen (PA), edema factor (EF), and lethal factor (LF). Among these proteins, PA has become the major focus of work on monoclonal antibodies and vaccines designed to treat or prevent anthrax infection since neither EF nor LF is capable of inducing cellular toxicity in its absence. Here, we present the development of a sensitive, precise, and biologically relevant bioassay platform capable of quantifying antibody-mediated PA neutralization. This bioassay is based on the ability of PA to bind and shuttle EF, a bacterial adenylate cyclase, into mammalian cells leading to an increase in cAMP that can be quantified using a sensitive chemiluminescent ELISA. The results of this study indicate that the cAMP-induction assay possesses the necessary performance characteristics for use as both a potency-indicating release assay in a quality control setting and as a surrogate pharmacodynamic marker for ensuring the continued bioactivity of therapeutic antibodies against PA during clinical trials.

Comparison of microarray-based mRNA profiling technologies for identification of psychiatric disease and drug signatures.

The gene expression profiles of human postmortem parietal and prefrontal cortex samples of normal controls and patients with bipolar disease, or human neuroblastoma flat (NBFL) cells treated with the mood-stabilizing drug, valproate, were used to compare the performance of Affymetrix oligonucleotide U133A GeneChips and Agilent Human 1 cDNA microarrays. Among those genes represented on both platforms, the oligo array identified 26-53% more differentially expressed genes compared to the cDNA array in the three experiments, when identical fold change and t-test criteria were applied. The increased sensitivity was primarily the result of more robust fold changes measured by the oligonucleotide system. Essentially all gene changes overlapping between the two platforms were co-directional, and ranged from 4 to 19% depending upon the amount of biological variability within and between the comparison groups. Q-PCR validation rates were virtually identical for the two platforms, with 23-24% validation in the prefrontal cortex experiment, and 56% for both platforms in the cell culture experiment. Validated genes included dopa decarboxylase, dopamine beta-hydroxylase, and dihydropyrimidinase-related protein 3, which were decreased in NBFL cells exposed to valproate, and spinocerebellar ataxia 7, which was increased in bipolar disease. The modest overlap but similar validation rates show that each microarray system identifies a unique set of differentially expressed genes, and thus the greatest information is obtained from the use of both platforms.

Perceived racial discrimination, but not mistrust of medical researchers, predicts the heat pain tolerance of African Americans with symptomatic knee osteoarthritis.

OBJECTIVE: Studies have shown that perceived racial discrimination is a significant predictor of clinical pain severity among African Americans. It remains unknown whether perceived racial discrimination also alters the nociceptive processing of painful stimuli, which, in turn, could influence clinical pain severity. This study examined associations between perceived racial discrimination and responses to noxious thermal stimuli among African Americans and non-Hispanic Whites. Mistrust of medical researchers was also assessed given its potential to affect responses to the noxious stimuli. METHOD: One-hundred and 30 (52% African American, 48% non-Hispanic White) community-dwelling older adults with symptomatic knee osteoarthritis completed two study sessions. In session one, individuals provided demographic, socioeconomic, physical and mental health information. They completed questionnaires related to perceived lifetime frequency of racial discrimination and mistrust of medical researchers. In session two, individuals underwent a series of controlled thermal stimulation procedures to assess heat pain sensitivity, particularly heat pain tolerance. RESULTS: African Americans were more sensitive to heat pain and reported greater perceived racial discrimination as well as greater mistrust of medical researchers compared with non-Hispanic Whites. Greater perceived racial discrimination significantly predicted lower heat pain tolerance for African Americans but not non-Hispanic Whites. Mistrust of medical researchers did not significantly predict heat pain tolerance for either racial group. CONCLUSION: These results lend support to the idea that perceived racial discrimination may influence the clinical pain severity of African Americans via the nociceptive processing of painful stimuli.