Utilizing cost-effective portable equipment to enhance COVID-19 variant tracking both on-site and at a large scale.

Despite optimistic predictions on the eventual end of COVID-19 (Coronavirus Disease 2019), caution is necessary regarding the emergence of new variants to sustain a positive outlook and effectively address any potential future outbreaks. However, ongoing efforts to track COVID-19 variants are concentrated in developed countries and unique social practices and remote habitats of indigenous peoples present additional challenges. By combining small-sized equipment that is easily accessible and inexpensive, we performed SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) whole genome sequencing and measured the sample-to-answer time and accuracy of this portable variant tracking tool. Our portable design determined the variant of SARS-CoV-2 in an infected individual within 9 hours and 15 minutes without external power or internet connection, surpassing the speed of previous portable tools. It took only 16 minutes to complete sequencing run, whole genome assembly, and lineage determination using a single standalone laptop. We then demonstrated the capability to produce 289 SARS-CoV-2 whole genome sequences in a single portable sequencing run, representing a significant improvement over an existing throughput of 96 sequences per run. We verified the accuracy of portable sequencing by comparison with two other independent sequencing methods. We showed that our high-throughput data consistently represented the circulating variants in Los Angeles, United States, when compared with publicly available sequences. Our scheme is designed to be flexible, rapid, and accurate, making it a valuable tool for large-scale surveillance operations in low- and middle-income countries as well as targeted surveys for vulnerable populations in remote locations.IMPORTANCEThere have been significant efforts to track COVID-19 (Coronavirus Disease 2019) variants, accumulating over 15 million SARS-CoV-2 sequences as of 2023. However, the distribution of global survey data is highly skewed, with nearly half of all countries having inadequate or low levels of genomic surveillance. In addition, indigenous peoples face more severe threats from COVID-19, due to their generally remote residence and unique social practices. Cost-effective portable sequencing tools have been used to investigate Ebola and Zika outbreaks. However, these tools have a sample-to-answer time of around 24 hours and require an internet connection for data transfer to an off-site cloud server. In our study, we rapidly determined COVID-19 variants using only small and inexpensive equipment, with a completion time of 9 hours and 15 minutes. Furthermore, we produced 289 near-full-length SARS-CoV-2 genome sequences from a single portable Nanopore sequencing run, representing a threefold increase in throughput compared with existing Nanopore sequencing methods.

Neurotropism of SARS-CoV-2: A Pathological Examination of Neurosurgical Specimens.

BACKGROUND AND OBJECTIVES: Neurological manifestations may occur in more than 80% of patients hospitalized with COVID-19 infection, including severe disruptions of the central nervous system (CNS), such as strokes, encephalitis, or seizures. Although the primary pathophysiological mechanism for the effects of COVID-19 in CNS remains unknown, evidence exists for both direct injury from neuroinvasion and indirect effects from disruptions in systemic inflammatory and coagulation pathways. In this study, we analyzed CNS tissue from living patients to better understand these processes. METHODS: With institutional review board approval and patient consent, samples that would be otherwise discarded from patients with active or recent (within 6 days of surgery) COVID-19 infection undergoing neurosurgical intervention were collected and tested for the presence of SARS-CoV-2 using immunohistochemistry, in situ hybridization, electron microscopy, and reverse transcription polymerase chain reaction. RESULTS: Five patients with perioperative mild-to-moderate COVID-19 infection met inclusion criteria (2 male, 3 female; mean age 38.8 ± 13.5 years). Neurosurgical diagnoses included a glioblastoma, a ruptured arteriovenous malformation, a ruptured posterior inferior cerebellar artery aneurysm, a middle cerebral artery occlusion, and a hemorrhagic pontine cavernous malformation. Samples analyzed included the frontal lobe cortex, olfactory nerve, arteriovenous malformation/temporal lobe parenchyma, middle cerebral artery, cerebellum, and cavernous malformation/brainstem parenchyma. Testing for the presence of SARS-CoV-2 was negative in all samples. CONCLUSION: The CNS is likely not a significant viral reservoir during mild-to-moderate COVID-19 infection, although direct neuroinvasion is not definitively excluded. Additional testing to help elucidate the relative contributions of direct and indirect pathways for CNS injury from COVID is warranted.

SARS-CoV-2 viral variants can rapidly be identified for clinical decision making and population surveillance using a high-throughput digital droplet PCR assay.

Epidemiologic surveillance of circulating SARS-CoV-2 variants is essential to assess impact on clinical outcomes and vaccine efficacy. Whole genome sequencing (WGS), the gold-standard to identify variants, requires significant infrastructure and expertise. We developed a digital droplet polymerase chain reaction (ddPCR) assay that can rapidly identify circulating variants of concern/interest (VOC/VOI) using variant-specific mutation combinations in the Spike gene. To validate the assay, 800 saliva samples known to be SARS-CoV-2 positive by RT-PCR were used. During the study (July 2020-March 2022) the assay was easily adaptable to identify not only existing circulating VAC/VOI, but all new variants as they evolved. The assay can discriminate nine variants (Alpha, Beta, Gamma, Delta, Eta, Epsilon, Lambda, Mu, and Omicron) and sub-lineages (Delta 417N, Omicron BA.1, BA.2). Sequence analyses confirmed variant type for 124/124 samples tested. This ddPCR assay is an inexpensive, sensitive, high-throughput assay that can easily be adapted as new variants are identified.

Surveillance of Severe Acute Respiratory Syndrome Coronavirus 2 and Variants Using Digital Droplet Polymerase Chain Reaction at a Large University and Healthcare System in California.

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants with different infectivity, transmission potential, and morbidity change the characteristics of local epidemics and affect vaccine effectiveness. As part of the University of Southern California COVID-19 Pandemic Research Center's efforts to understand, control, and inform local community on coronavirus disease 2019 (COVID-19), we implemented a SARS-CoV-2 surveillance program among students, employees, and USC Keck Medical Center patients. We present the epidemiology and distribution of SARS-CoV-2 and its variants among the population. Methods: We used digital droplet reverse-transcriptase polymerase chain reaction (PCR) to analyze in real-time remnant SARS-CoV-2 PCR-positive saliva specimens stored at the USC Keck Medicine laboratory between September 2020 and April 2022. Samples were tested for the original strain (A20) and 9 SARS-CoV-2 variants: α(B.1.1.7, Q.1-Q.8), ß(B.1.351, B.1.351.2, B.1.351.3), γ(P.1, P.1.1, P.1.2), δ(B.1.617.2), δ+(or δ417N), ε(B.1.427 and B.1.429), η(B.1.525), λ(C.37) and ο(B.1.1.529, ΒΑ.1, BA.2). We reviewed deidentified health information from positive cases including demographics, history of COVID-19 (eg, symptoms, hospitalizations, and repeat infections), and COVID-19 vaccination status. Results: We reviewed 1169 cases and determined the variant type of 482 specimens: 77 specimens were original strain, 119 "Delta", 165 "Omicron". The original strain was detected during the third and fourth quarters of 2020. The Delta variant appeared during the second quarter of 2021, whereas Omicron appeared in the fourth quarter of 2021. Conclusions: Prospectively tracking SARS-CoV-2 variants in a university population and a hospital system, utilizing a low-cost, high-throughput PCR assay, was feasible. Local variant monitoring remains important to inform prevention and control efforts among university and clinical settings.

Aging as a Productive Process: A Critical Analysis of Aging Policy in Newfoundland and Labrador, Canada.

There has been a growing focus on healthy aging in the political agenda. Discourses contained within policy documents have the potential to shape our notions of healthy aging and well-being. This comprehensive critical document analysis of provincial aging policies in Newfoundland and Labrador (2006-2015) contributes to a larger research study exploring aging women's notions of health and the body in relation to the aging process. The findings highlight how healthy aging discourses focus on the concept of productivity and how a certain type of health is required for ongoing contribution. The paper concludes by arguing that if healthy aging is framed around one's ability to remain productive, notions of health will remain limited to an externalized measure of output versus subjective experience of well-being.

High-precision and cost-efficient sequencing for real-time COVID-19 surveillance.

COVID-19 global cases have climbed to more than 33 million, with over a million total deaths, as of September, 2020. Real-time massive SARS-CoV-2 whole genome sequencing is key to tracking chains of transmission and estimating the origin of disease outbreaks. Yet no methods have simultaneously achieved high precision, simple workflow, and low cost. We developed a high-precision, cost-efficient SARS-CoV-2 whole genome sequencing platform for COVID-19 genomic surveillance, CorvGenSurv (Coronavirus Genomic Surveillance). CorvGenSurv directly amplified viral RNA from COVID-19 patients' Nasopharyngeal/Oropharyngeal (NP/OP) swab specimens and sequenced the SARS-CoV-2 whole genome in three segments by long-read, high-throughput sequencing. Sequencing of the whole genome in three segments significantly reduced sequencing data waste, thereby preventing dropouts in genome coverage. We validated the precision of our pipeline by both control genomic RNA sequencing and Sanger sequencing. We produced near full-length whole genome sequences from individuals who were COVID-19 test positive during April to June 2020 in Los Angeles County, California, USA. These sequences were highly diverse in the G clade with nine novel amino acid mutations including NSP12-M755I and ORF8-V117F. With its readily adaptable design, CorvGenSurv grants wide access to genomic surveillance, permitting immediate public health response to sudden threats.

The female aging body: A systematic review of female perspectives on aging, health, and body image.

While most body image research has focused on young female populations, evidence has shown that as few as 12% of older women are satisfied with their body size. Recent studies have also highlighted how anti-aging discourses are promoting unrealistic body norms, which have shown to contribute to poor body image and altered health behaviors. A systematic review of empirical studies focused on older women's perspectives of health, body image, and the aging body is presented. Findings support that body image is a persistent, lifelong issue for women and should be considered when implementing healthy aging policies and practices.

Gain of TP53 Mutation in Imatinib-treated SDH-Deficient Gastrointestinal Stromal Tumor and Clinical Utilization of Targeted Next-generation Sequencing Panel for Therapeutic Decision Support.

Patients with succinate dehydrogenase (SDH)-deficient gastrointestinal stromal tumor (GIST) have few therapeutic options. Despite lack of KIT or platelet-derived growth factor receptor A (PDGFRA) driver mutations, SDH-deficient GISTs display strong expression of KIT by immunohistochemistry and these patients are often treated with tyrosine kinase inhibitors, including imatinib as a first-line therapy. Using a targeted next-generation sequencing panel of mutation hotspots of 50-clinically relevant genes, we investigated (1) concurrence of somatic/actionable mutations and (2) tumor molecular evolution by comparing 2 resection specimens 1.5 years apart while the patient was on imatinib adjuvant therapy. We found the tumors did not harbor KIT, PDGFRA, or any other clinically actionable mutations. However, a TP53 mutation (c.422G>A; p.C141Y) was detected in the second recurrent lesion. This represents the first study to monitor the molecular evolution of a SDH-deficient GIST during adjuvant treatment. These findings emphasize the critical need for next-generation sequencing testing before initiating targeted therapy.

Sterilizing photocurable materials by irradiation: preserving UV-curing properties of photopolymers following E-beam, gamma, or X-ray exposure.

We have developed novel photopolymer gels to function as separators in blood collection tubes. By incorporating antioxidants such as α-tocopherol and nitroxides (TEMPO and TEMPOL), the new formulation can be sterilized with electron beam or gamma rays at a dose level of 17 kGy, without inducing premature curing of the photopolymers. For the blood separator gels that contain α-tocopherol, our results show that α-tocopherol plays a decisive role in impeding C-centered free radical propagation reactions through an H-transfer mechanism. This mechanism involves the transfer of an H-atom from the hydroxyl group (OH) of α-tocopherol to the propagating C-centered radical leading to the termination of the polymerization. The sterilization radiation-induced premature curing of the photopolymer was also prevented in the blood separator gel containing nitroxides. For the gels containing TEMPO or TEMPOL, inhibition of the premature curing was achieved through an addition reaction or an H-transfer reaction, respectively. Our results also show that while α-tocopherol is not a contributing factor in the subsequent (time-of-use) UV curing of the gels, nitroxides enhance the UV curing process through nitroxide-mediated living free radical polymerization reactions leading to a decrease in UV curing time. The photopolymer separator gels are shown to function advantageously in clinical laboratory testing, especially for cell-free DNA measurements in blood.

Facklamia Species as an Underrecognized Pathogen.

Facklamia species are a rarely reported etiology of clinical infection with few cases described in literature. However, the prevalence of infection may be underestimated due to challenges in species identification. We describe 3 cases of Facklamia species bacteremia and the unique microbiologic aspects inherent to this genus that make it particularly challenging to identify. In addition, given the unique susceptibility profile of Facklamia species, we discuss the importance of fully identifying this organism when it is a suspected as a pathogen, to optimize therapy based on its distinct antibiotic resistance profile.

Application of Nuclear Magnetic Resonance to Detect Toxigenic Clostridium difficile from Stool Specimens: A Proof of Concept.

We evaluated the performance of an early prototype core molecular mirroring nuclear magnetic resonance detection platform (Mentor-100) to detect toxigenic Clostridium difficile from stool. This technology uses customized nanoparticles bound to target specific oligonucleotide probes that form binaries in the presence of nucleic acid from the target microorganism. Liquid patient stool specimens were seeded with C. difficile or other Clostridium species to determine the analytical sensitivity and specificity. Samples underwent nucleic acid extraction and target amplification with probes conjugated with iron nanoparticles. Signal from nuclear magnetic resonance spin-spin relaxation time was measured to detect the presence or absence of toxigenic C. difficile. The limit of detection was <180 colony forming units per reaction of toxigenic C. difficile. No cross-reactivity was observed with nontoxigenic C. difficile, Clostridium sordellii, Clostridium perfringens, Bacillus subtilis, or Paenibacillus polymyxa at 108 colony forming units/mL. Correlation studies using frozen stool samples yielded a sensitivity of 88.4% (61 of 69) and a specificity of 87.0% (40 of 46) as compared with a commercial PCR assay for C. difficile. The area under the curve in the receiver operating characteristic curve analysis was 0.922. The prototype molecular mirroring platform showed promising performance for pathogen detection from clinical specimens. The platform design has the potential to offer a novel, low-cost alternative to currently available nucleic acid-based tests.

Reproducing stigma: Interpreting "overweight" and "obese" women's experiences of weight-based discrimination in reproductive healthcare.

Amidst a barrage of policy documents, bio-medical research, and press items concerned with the "crisis" of obesity, a growing scholarship is concerned with what has come to be known as "obesity stigma." This scholarship hails from a range of sources including critical obesity scholars who problematize the idea of obesity as a health concern, as well as from "mainstream" organizations and researchers who, while maintaining obesity is a world-wide health problem, also argue that "obese" people are the targets of discrimination. In this paper, we analyze both interpretations of obesity stigma, particularly as that stigma applies to obese women's experiences of accessing and receiving reproductive care. We describe a qualitative study conducted with 24 overweight and obese women in 2 Canadian cities. Participants related overt and covert experiences of stigma when accessing reproductive care founded in healthcare practitioners' focus on fetal risk and "mother-blame" which, though partially evidence-based, was interpreted by participants as discriminatory. As such, we maintain that any true interruption of obesity stigma in the reproductive healthcare interaction requires a bridge between critical and mainstream scholarship, and careful attention to the risk-based foci in clinical settings which can be interpreted by clients as moralizing.

The value of a multiplexed gastrointestinal pathogen panel in 2 distinct patient populations.

We assess the value of the Luminex xTAG Gastrointestinal Pathogen Panel (GPP) in 2 different patient populations: an uninsured, indigent population seeking primary care, and a tertiary care hospital specializing in surgical, transplant, and oncology care. Stool specimens collected April to August 2013 for infectious workup were tested on the GPP, and discordant results were further analyzed by alternative methods. Compared to the tertiary care setting, stool pathogen detection was nearly twice as frequent in the primary care setting (25% versus 14%; P<0.05) with a broader array of pathogens detected (15 versus 4). Overall, the greatest value of the GPP was in detection of viral causes of gastroenteritis that were not routinely sought and in detection of Campylobacter spp. when patients presented late in the disease course. Application of a GPP should consider the characteristics of the patient population to maximize its clinical utility in different healthcare settings.

Improving collaborative care in managing eating disorders: a pilot study.

INTRODUCTION: The purpose of this pilot study was to evaluate the impact of a continuing interprofessional educational workshop focused on eating disorders in a rural area in Newfoundland and Labrador (NL), Canada. The pilot study helped determine if the eating disorder workshop was feasible for implementation to a broader audience. A conceptual model developed by our eating disorder team and described in the article guided this innovative program. METHODS: The intensive 2-day workshop was piloted in one community with 41 health and education professionals in attendance. A key element was the focus on creating and sustaining collaborative care for eating disorders. Participants completed pre-post workshop measures of interprofessional attitudes and skills, self-reported knowledge, confidence, and intention to change practice (post questionnaire only). A 6-month follow-up survey measured self-reported practice change. RESULTS: There were significant positive changes in interprofessional attitudes and skills as well as knowledge and confidence in collaborative management of eating disorders. Post-workshop, 69% (n = 24/35) of participants indicated intention to change practice, and on follow-up, 7 of 10 respondents reported implementing changes in practice as a result of the workshop. Low response rate at follow-up was a limitation. DISCUSSION: Results support the impact of the workshop in improving knowledge, confidence, and attitudes toward collaboration and changing practice and the value of implementing the program province-wide.

Differentiating squamous cell carcinoma of the cervix and epithelioid trophoblastic tumor.

BACKGROUND: Epithelioid trophoblastic tumor (ETT) is a recently described subtype of gestational trophoblastic neoplasia (GTN). Its diagnosis requires a high level of suspicion because it is often mistaken for more common cervical or uterine corpus epithelial neoplasms. CASE: This is a 39-year-old woman who presented with a cervical mass and positive human chorionic gonadotropin and was diagnosed with both locally advanced squamous cell cervical carcinoma and nonmetastatic GTN. She was treated unsuccessfully with concurrent intravenous cisplatin plus pelvic radiation and single-agent intravenous methotrexate. A retrospective review of the cervical biopsy using immunohistochemistry as well as genotyping of the tumor changed the original diagnosis to ETT. It is known that ETT is relatively unresponsive to chemotherapy compared with most other types of GTN; therefore, surgery would have been the optimal treatment. She died despite multiple salvage chemotherapies. CONCLUSIONS: Malignant GTN is one of the most curable gynecologic malignancies; however, its correct diagnosis is critical for the appropriate treatment. It can be easily misdiagnosed as a carcinoma because of their morphologic similarity. Genetic fingerprinting and immunohistochemistry are potentially valuable tools to confirm the diagnosis of ETT.

Extra copies of chromosome 2 are a recurring aberration in ALK-negative lymphomas with anaplastic morphology.

The purpose of this study was to evaluate fluorescence in situ hybridization abnormalities of the 2p23 anaplastic lymphoma kinase (ALK) gene loci in lymphomas with anaplastic morphology. We studied 24 anaplastic large cell lymphomas (ALCL) classified by World Health Organization criteria [17 primary nodal/systemic (10 ALK+, 7 ALK-), seven primary cutaneous], and 17 additional non-Hodgkin's lymphomas [one ALK+ B-lineage lymphoma, 14 ALK- diffuse large B-cell lymphomas (seven anaplastic variants, five nonanaplastic, two secondary CD30+), two follicular lymphomas]. ALK- lymphomas with anaplastic morphology showed extra nonrearranged anaplastic lymphoma kinase gene loci (P=0.004) due to trisomy 2 irrespective of the following factors: B or T/null phenotype (P=0.315), diagnostic categories of systemic or cutaneous ALCL or the above-mentioned B-cell lymphomas (P=0.131), and CD30 positivity by immunohistochemistry (P=1.000). Trisomy 2 was absent in all ALK+ lymphomas (P=0.009), which showed rearranged ALK gene loci (P<0.001). Whether trisomy 2 is a primary or secondary event that leads to ALK- lymphomas cannot be determined from this study. Its presence in secondary B-cell lymphomas suggests that trisomy 2 may be a secondary cytogenetic aberration in lymphomas in general. Further investigation of this finding is necessary to further our understanding of the heterogeneous group of ALK- lymphomas.

Endogenous opioids and chronic pain intensity: interactions with level of disability.

OBJECTIVE: To test whether endogenous opioid antinociceptive system dysfunction evidenced in response to acute pain stimuli is associated with increased clinical pain intensity in chronic pain sufferers, and to determine whether this association is moderated by disability level. DESIGN: A double-blind, placebo-controlled, randomized crossover design. Subjects underwent laboratory acute finger pressure pain stimulation and ischemic pain stimulation under placebo and under opioid blockade with naloxone. The primary independent measures, reflecting degree of endogenous opioid antinociception, were opioid Blockade Effects derived to reflect the change elicited by naloxone in pain intensity ratings for the acute pain tasks. High and Low Disability groups were derived based on Pain Disability Index scores to allow examination of the influence of disability level on the relationship between Blockade Effects and chronic pain intensity. SUBJECTS: Twenty-eight chronic low back pain sufferers. OUTCOME MEASURE: Seven-day diary ratings of overall chronic pain intensity based on McGill Pain Questionnaire-Short Form total scores. RESULTS: Greater daily chronic pain intensity was associated with greater placebo acute pain sensitivity in the laboratory (P < 0.05). Positive Blockade Effects (ie, presence of opioid analgesia) were associated as expected with lower placebo-condition acute pain sensitivity in the laboratory (P < 0.05). In main effects analyses, Blockade Effects were not associated significantly with daily chronic pain intensity. This absence of overall main effects was accounted for by significant opposing interactions between disability level and Blockade Effects (P < 0.05). Negative Blockade Effects (ie, absence of endogenous opioid analgesia to acute pain) in the High Disability group were associated with greater daily chronic pain intensity, consistent with the hypothesized effects of chronic pain-related opioid dysfunction. In contrast, Positive Blockade Effects (ie, effective opioid analgesia to acute pain) were associated with higher daily chronic pain intensity in the Low Disability group. CONCLUSIONS: These results suggest that endogenous opioid antinociceptive system dysfunction may contribute to elevated acute and chronic pain sensitivity among more disabled chronic pain patients. Among less disabled patients, chronic pain may serve as a primer producing up-regulated opioid antinociceptive responses to acute pain

Definition of a region of loss of heterozygosity at chromosome 11q23.3-25 in head and neck squamous cell carcinoma using laser capture microdissection technique.

To date, loss of heterozygosity (LOH) studies on HNSCC have had limited success in identifying a confined region of loss on chromosome 11q partially due to the heterogeneous nature of tumor tissue examined. Additionally, little is known about the role of the 11q allelic deletion in HNSCC tumorigenesis and current reports are conflicting. The aim of this study was to better define LOH at distal 11q by using combination of a pure cell population procured by laser capture microdissection (LCM) and subsequent sensitive PCR amplification of polymorphic microsatellites. This study analyzed HNSCC for LOH using a panel of 5 microsatellite markers spanning 11q23-25. Thirty-four paired DNA samples from tumor and autologous normal tissue were harvested by LCM technique to ensure a pure cell population for PCR amplification. Approximately 2000 to 3000 cells were procured from each sample. Twenty-one of 34 cases (62%, P < 0.001) showed LOH on at least one of the loci examined. The highest frequency of LOH was found at the 11q23.3-25 segment, with 44% at marker D11S968 and 35% at marker D11S1316. A distinct novel region of frequent LOH at 11q23.3-25, defined by D11S1316 and D11S968, was identified. No allelic loss was found in any normal squamous tissue samples. To study LOH in HNSCC, combination of pure cell population procurement by LCM and sensitive PCR provides a more accurate approach than the conventional method using a bulk of heterogeneous tissue. A novel region of LOH at 11q23.3-25 was defined. LOH in this region may harbor putative tumor suppressor gene(s) critical for HNSCC. Furthermore, these allelic losses were not found in any non-neoplastic squamous tissue samples, clarifying prior discrepant data.

The relationship between resting blood pressure and acute pain sensitivity in healthy normotensives and chronic back pain sufferers: the effects of opioid blockade.

Resting blood pressure is inversely correlated with acute pain sensitivity in healthy normotensives. This study tested: (1) whether endogenous opioid activity is necessary for this adaptive relationship to occur, (2) whether this relationship is altered in chronic low back pain (LBP), and (3) whether endogenous opioid dysfunction underlies any such alterations. Fifty-one pain-free normotensives and 44 normotensive chronic LBP sufferers received opioid blockade (8 mg naloxone i.v.) or placebo blockade (saline) in randomized, counterbalanced order in separate sessions. During each session, subjects participated in a 1-min finger pressure (FP) pain task followed by an ischemic (ISC) forearm pain task. Among pain-free normotensives, elevated resting systolic (SBP) and diastolic (DBP) blood pressure were associated with significantly higher ISC pain thresholds (P values <0.05). Elevated SBP was also associated with significantly lower FP pain ratings (P<0.05). Opioid blockade had no significant effect on the BP-pain relationships detected (P values >0.10). In combined groups analyses, a significant subject typexSBP interaction (P<0.005) was found on ISC pain threshold: elevated SBP was associated with higher pain threshold in pain-free controls, but with lower pain threshold in LBP subjects. Although subject typexBP interactions on FP and ISC pain ratings were not significant, inclusion of LBP subjects in these analyses resulted in the overall relationship between BP and pain sensitivity becoming positive (P values <0.05). Opioid blockade exerted no significant main or interaction effects in these combined groups analyses (p values >0.10). Higher DBP was associated with greater clinical pain intensity among the LBP subjects (P<0.001). Overall, these results suggest: (1) endogenous opioids do not mediate the inverse relationship between resting blood pressure and acute pain sensitivity in pain-free normotensives; (2) the BP-pain sensitivity relationship is altered in chronic pain, suggesting dysfunction in pain regulatory systems, and (3) these alterations are not related to opioid dysfunction.