465 research outputs found
Activation of the descending pain modulatory system using cuff pressure algometry:Back translation from man to rat
Temporal Aspects of Endogenous Pain Modulation During a Noxious Stimulus Prolonged for 1 Day
Background
This study investigated (a) if a prolonged noxious stimulus (24âhr topical capsaicin) in healthy adults would impair central pain inhibitory and facilitatory systems measured as a reduction in conditioned pain modulation (CPM) and enhancement of temporal summation of pain (TSP) and (b) if acute pain relief or exacerbation (cooling and heating the capsaicin patch) during the prolonged noxious stimulus would affect central pain modulation. Methods
Twentyâeight participants (26.2 ± 1.0 years; 12 women) wore a transdermal 8% capsaicin patch on the forearm for 24 hr. Data were collected at baseline (Day 0), 1 hr, 3 hr, Day 1 (postâcapsaicin application) and Day 3/4 (postâcapsaicin removal) that included capsaicinâevoked pain intensity, heat pain thresholds (HPTs), TSP (10 painful cuff pressure stimuli on leg) and CPM (cuff pressure pain threshold on the leg prior vs. during painful cuff pressure conditioning on contralateral leg). After 3 hr, cold (12°C) and heat (42°C) stimuli were applied to the capsaicin patch to transiently increase and decrease pain intensity. Results
Participants reported moderate pain scores at 1 hr (2.5 ± 2.0), 3 hr (3.7 ± 2.4), and Day 1 (2.4 ± 1.8). CPM decreased 3âhr postâcapsaicin (p = .001) compared to Day 0 and remained diminished while the capsaicin pain score was reduced (0.4 ± 0.7, p \u3c .001) and increased (6.6 ± 2.2, p \u3c .001) by patch cooling and heating. No significant differences occurred for CPM during patch cooling or heating compared to initial 3HR; however, CPM during patch heating was reduced compared with patch cooling (p = .01). TSP and HPT did not change. Conclusions
This prolonged experimental pain model is useful to provide insight into subacute pain conditions and may provide insight into the transition from acute to chronic pain. Significance
During the early hours of a prolonged noxious stimulus in healthy adults, CPM efficacy was reduced and did not recover by temporarily removing the ongoing pain indicating a less dynamic neuroplastic process
Exercise-induced hypoalgesia in young adult females with long-standing patellofemoral pain â A randomized crossover study
Conditioning pain modulation reduces pain only during the first stimulation of the temporal summation of pain paradigm in healthy participants
Resisted adduction in hip neutral is a superior provocation test to assess adductor longus pain:an experimental pain study
The criterion of long-standing groin pain diagnoses in athletes usually relies on palpation and clinical tests. An experimental pain model was developed to examine the clinical tests under standardized conditions. Pain was induced by hypertonic saline injected into the proximal adductor longus (AL) tendon or rectus femoris (RF) tendon in 15 healthy male participants. Isotonic saline was injected contralaterally as a control. Pain intensity was assessed on a visual analog scale (VAS). Resisted hip adduction at three different angles and trunk flexion were completed before, during, and after injections. Pain provocation in the presence of experimental pain was recorded as a true positive compared with pain provocation in the non-pain conditions. Similar peak VAS scores were found after hypertonic saline injections into the AL and RF and both induced higher VAS scores than isotonic saline (P<0.01). Adduction at 0° had the greatest positive likelihood ratio (+LR=2.8, 95%CI: 1.09-7.32) with 45° (-LR=0.0, 95%CI: 0.00-1.90) and 90° (-LR=0.0, 95%CI: 0.00-0.94) having the lowest negative LR. This study indicates that the 0° hip adduction test resisted at the ankles optimizes the diagnostic procedure without compromising diagnostic capacity to identify experimental groin pain. Validation in clinical populations is warranted
Comparability of radiocarbon measurements in dissolved inorganic carbon of seawater produced at ETH-Zurich
Radiocarbon observations (Î14C) in dissolved inorganic carbon (DIC) of seawater provide useful information about ocean carbon cycling and ocean circulation. To deliver high-quality observations, the Laboratory of Ion Beam Physics (LIP) at ETH-Zurich developed a new simplified method allowing the rapid analysis of radiocarbon in DIC of small seawater samples, which is continually assessed by following internal quality controls. However, a comparison with externally produced 14C measurements to better establish an equivalency between methods was still missing. Here, we make the first intercomparison with the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility based on 14 duplicate seawater samples collected in 2020. We also compare with prior deep-water observations from the 1970s to 1990s. The results show a very good agreement in both comparisons. The mean Î14C of 12 duplicate samples measured by LIP and NOSAMS were statistically identical within one sigma uncertainty while two other duplicate samples agreed within two sigma. Based on this small number of duplicate samples, LIP values appear to be slightly lower than the NOSAMS values, but more measurements will be needed for confirmation. We also comment on storage and preservation techniques used in this study, including the freezing of samples collected in foil bags
Preoperative neuropathic pain like symptoms and central pain mechanisms in knee osteoarthritis predicts poor outcome 6 months after total knee replacement surgery
Preoperative pain characteristics in osteoarthritis (OA) patients may explain persistent pain after total knee replacement (TKR). Fifty patients awaiting TKR and 22 asymptomatic controls were recruited to evaluate the degree of neuropathic pain symptoms and pain sensitisation. OA patients were pain phenotyped into two groups based on the PainDETECT questionnaire: High PainDETECT group (scores â„19) indicating neuropathic pain-like symptoms, Low PainDETECT group (scores 19) indicating nociceptive or mixed pain.Cuff algometry assessing pain detection thresholds (PDT) and pain tolerance (PTT) was conducted on the lower legs. Temporal summation of pain (TSP) was assessed using ten sequential cuff stimulations and a von Frey stimulator. Conditioning pain modulation was assessed by cuff pain conditioning on one leg and parallel assessment of PDT on the contralateral leg. Pressure pain thresholds (PPTs) were recorded by pressure handheld algometry local and distant to the knee. Knee pain intensity (VAS) and pain assessment were collected before and 6 months post-TKR. 30% of patients demonstrated neuropathic pain-like symptoms (High PainDETECT group). Facilitated TSP and reduced PPTs distant to the knee were found in High PainDETECT group compared to Low PainDETECT group and healthy controls groups (
Simulating estimation of California fossil fuel and biosphere carbon dioxide exchanges combining in situ tower and satellite column observations
We report simulation experiments estimating the uncertainties in California regional fossil fuel and biosphere CO2 exchanges that might be obtained by using an atmospheric inverse modeling system driven by the combination of groundâbased observations of radiocarbon and total CO2, together with columnâmean CO2 observations from NASA's Orbiting Carbon Observatory (OCOâ2). The work includes an initial examination of statistical uncertainties in prior models for CO2 exchange, in radiocarbonâbased fossil fuel CO2 measurements, in OCOâ2 measurements, and in a regional atmospheric transport modeling system. Using these nominal assumptions for measurement and model uncertainties, we find that flask measurements of radiocarbon and total CO2 at 10 towers can be used to distinguish between different fossil fuel emission data products for major urban regions of California. We then show that the combination of flask and OCOâ2 observations yields posterior uncertainties in monthlyâmean fossil fuel emissions of ~5â10%, levels likely useful for policy relevant evaluation of bottomâup fossil fuel emission estimates. Similarly, we find that inversions yield uncertainties in monthly biosphere CO2 exchange of ~6%â12%, depending on season, providing useful information on net carbon uptake in California's forests and agricultural lands. Finally, initial sensitivity analysis suggests that obtaining the above results requires control of systematic biases below approximately 0.5âppm, placing requirements on accuracy of the atmospheric measurements, background subtraction, and atmospheric transport modeling
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Assessing fossil fuel COâ emissions in California using atmospheric observations and models
Analysis systems incorporating atmospheric observations could provide a powerful tool for validating fossil fuel CO2 (ffCO2) emissions reported for individual regions, provided that fossil fuel sources can be separated from other CO2 sources or sinks and atmospheric transport can be accurately accounted for. We quantified ffCO2 by measuring radiocarbon (14C) in CO2, an accurate fossil-carbon tracer, at nine observation sites in California for three months in 2014â15. There is strong agreement between the measurements and ffCO2 simulated using a high-resolution atmospheric model and a spatiotemporally-resolved fossil fuel flux estimate. Inverse estimates of total in-state ffCO2 emissions are consistent with the California Air Resources Board's reported ffCO2 emissions, providing tentative validation of California's reported ffCO2 emissions in 2014â15. Continuing this prototype analysis system could provide critical independent evaluation of reported ffCO2 emissions and emissions reductions in California, and the system could be expanded to other, more data-poor regions
Assessing fossil fuel CO_2 emissions in California using atmospheric observations and models
Analysis systems incorporating atmospheric observations could provide a powerful tool for validating fossil fuel CO_2 (ffCO_2) emissions reported for individual regions, provided that fossil fuel sources can be separated from other CO_2 sources or sinks and atmospheric transport can be accurately accounted for. We quantified ffCO_2 by measuring radiocarbon (^(14)C) in CO_2, an accurate fossil-carbon tracer, at nine observation sites in California for three months in 2014â15. There is strong agreement between the measurements and ffCO_2 simulated using a high-resolution atmospheric model and a spatiotemporally-resolved fossil fuel flux estimate. Inverse estimates of total in-state ffCO_2 emissions are consistent with the California Air Resources Board's reported ffCO_2 emissions, providing tentative validation of California's reported ffCO_2 emissions in 2014â15. Continuing this prototype analysis system could provide critical independent evaluation of reported ffCO_2 emissions and emissions reductions in California, and the system could be expanded to other, more data-poor regions
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