Threshold Sensitivity Research Articles

Long-Term Follow-Up of Patients With Follicular Lymphoma Using Next Generation Sequencing to Detect Minimal Residual Disease

BackgroundFollicular lymphoma (FL) is a highly treatable, indolent non-Hodgkin lymphoma. Although FL is considered incurable, a patient without progression of disease by 24 months after treatment is predicted to have a survival consistent with persons without lymphoma. Using a sensitive assessment of minimal residual disease (MRD), we tested the hypothesis that MRD monitoring can predict long term remissions. MethodsUnselected patients who were in a clinical remission for at least 24 months after their last treatment were enrolled and monitored prospectively for MRD detectability using a sensitive next-generation sequencing assay (clonoSEQ, Adaptive Biotechnologies, Seattle, WA). ResultsForty-seven consecutive patients were monitored. We evaluated the MRD thresholds 10−4, 10−5, and 10−6 for the ability to predict long-term remissions in this cohort and determined that undetectable disease at 10−6 was the best predictor with a specificity and negative predictive value (NPV) of 70% and 100%, respectively. While 3 patients exhibited clinical disease progression during the course of the study, none of the 31 patients with persistent MRD undetectability at 10−6 experienced relapse. ConclusionsA significant proportion (31/47; 66.0%) of FL patients in clinical remission after ≥24 months following last therapy were undetectable at 10−6 by a sensitive assay of MRD. The threshold of sensitivity was 100%, specificity 70%, with a PPV of 19%, but a NPV of 100%. Although longer follow-up is needed for confirmation, many of these patients may continue to have durable complete remissions.

Predictive performance of corneal and lid margin sensitivity for dry eye disease: An investigator-masked, prospective, prognostic accuracy study

PurposeTo evaluate the prognostic ability of non-contact esthesiometry corneal and lid margin sensitivity measurements in detecting symptoms and signs of dry eye disease, as defined by the global consensus TFOS DEWS II criteria. MethodsA total of 87 community residents (58 females; mean ± SD age, 53 ± 16 years) were recruited in an investigator-masked, prospective, prognostic accuracy study. Dry eye symptomology, tear film parameters, and ocular surface characteristics were evaluated in a single clinical session, and non-contact esthesiometry corneal and lid margin sensitivity measurements performed by an independent masked assessor. ResultsOverall, 49 (56%) participants fulfilled the TFOS DEWS II criteria for dry eye disease, while 57 (66%) exhibited clinical symptoms, and 67 (77%) had positive signs. The prognostic abilities of corneal and lid margin sensitivity measurements were significantly greater than chance for the detection dry eye signs (both p ≤ 0.03), but not for symptoms or overall disease diagnosis (all p > 0.10). The Youden-optimal prognostic cut-offs for corneal and lid margin sensitivity thresholds were both ≥0.8 mbar for the detection of clinical dry eye signs. Lid margin sensitivity demonstrated marginally higher predictive performance than corneal sensitivity (C-statistic, 0.688 versus 0.658), and was significantly correlated with tear film stability, corneal, conjunctival and lid wiper staining (all p < 0.05). ConclusionsCorneal and lid margin sensitivity demonstrated moderate prognostic utility for detecting clinical dry eye signs. Future research is warranted to investigate the utility of incorporating non-contact esthesiometry in the workup for dry eye disease and neurotrophic keratopathy.

Abstract 5174: Organoids to predict treatment response in metastatic colorectal cancer (OPTIC)

Abstract Introduction: The inability to predict treatment response results in unnecessary toxicity, decreased efficacy and survival. There is a clinical need for an effective biomarker to select patients for cancer treatment. A promising biomarker for treatment efficacy is response testing on patient-derived organoids (PDOs). For metastatic colorectal cancer (mCRC), larger prospective studies are needed to evaluate the predictive value of standardized PDO screens. Methods: OPTIC is an ongoing prospective multicenter trial (NL61668.041.17, started 2018) that will evaluate the value of tumor PDOs in therapy response prediction. We establish PDOs for mCRC patients from newly obtained biopsies, prior to the start of treatment. We compare PDO sensitivity (area under drug response curve) with patient response measured by changes in biopsied metastatic lesion size on CT scans. Secondary outcome measures are RECIST response and progression-free survival. We evaluate the feasibility of using PDOs as a biomarker by examining drug screen availability in a clinically relevant timeframe of 4 weeks. From 2020 onwards, we incorporated whole genome sequencing (WGS) on fresh-frozen biopsies to correlate drug response in vitro and in vivo, to genetic tumor characteristics. Additionally, PDO screens with experimental drugs based on genetic alterations identified by WGS could be performed. Trial inclusion will continue until 85 PDOs from clinically evaluable patients for standard of care (SOC) treatment are established, with expected completion in Q1 2024. Results: Currently, 206 patients were included in 5 hospitals and 180 biopsies were taken. PDO establishment success gradually increased from 22% in 2018-2020 to 75% in 2023, yielding an overall success rate of 50% (n=84 PDOs and 13 in culture). Critical factors in optimizing culture success were replacement of several growth factors in the culture medium, reducing time to processing and more frequent handling of biopsies. We have established PDOs for comparing with patient response for the following treatment categories: 5-fluorouracil (n=4), CAPOX/FOLFOX (n=23), irinotecan/FOLFIRI (n=11), FOLFOXIRI (n=12), trifluridine/tipiracil (n=14), panitumumab (n=14), encorafenib-cetuximab (n=2), non-SOC drugs (n=4). We have successfully screened the first 8 PDOs in consistent technical triplicates and biological duplicates (R&amp;lt;0.88, p&amp;lt;0.02). WGS succeeded in 76% (n=75), primarily failing when tumor percentage was &amp;lt;20%. Conclusion: We improved PDO establishment success to 75% which is essential to facilitate the implementation of PDOs in clinical treatment. OPTIC will enhance the clinical application of PDOs by defining thresholds for PDO sensitivity and analyzing the diagnostic power for different treatments. To enable personalized treatment in clinical practice, PDO screening should guide mCRC treatment and result in enhanced chance of response and reduced over- and mistreatment. Citation Format: Lidwien P. Smabers, Emerens Wensink, Carla S. Verissimo, Mayke Doorn, Tao Yang, Timo Voskuilen, Yasmine Abouleila, Maarten A. Huismans, Liselot Valkenburg-van Iersel, Geert A. Cirkel, Elske C. Gootjes, Frank J. Jeurissen, Guus M. Bol, Hilde H. Nienhuis, Manon M. Braat, Bas Penning de Vries, Sjoerd G. Elias, Edwin Cuppen, Robert G. Vries, Onno Kranenburg, Miriam Koopman, Sylvia F. Boj, Jeanine M. Roodhart. Organoids to predict treatment response in metastatic colorectal cancer (OPTIC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5174.

Abstract 7473: Flotillin-2 ablation in T cells enhances antigen sensitivity and functionality

Abstract The membrane scaffolding protein flotillin-2 (Flot2) has been proposed to support receptor signaling, but its involvement in T cell receptor (TCR) signaling and T cell responses remains unclear. Here, we show that the deletion of Flot2 increases antigen sensitivity along with changes in surface TCR clustering, resulting in enhanced TCR signaling and effector function to weak TCR stimulation. T cell-specific Flot2-deficient mice showed enhanced proliferation and effector cytokine production in both CD4+ and CD8+ T cells, resulting in better control of tumor growth and infection. However, in vitro TCR stimulation with plate-bound anti-CD3 and soluble anti-CD28 showed increased TCR signaling and early activation of CD4+, but not CD8+ Flot2-deficient T cells upon weak stimulation. In addition, Flot2-deficient CD4+ T cells showed better in vitro polarization toward T helper 1 cells upon weak TCR stimulation, likely due to increased sensitivity of the TCR-triggering threshold. Changes in TCR clustering on the membrane have been suggested to influence the early detection of foreign stimuli and the formation of immune synapses. Flot2 ablation indeed increased the number of membrane TCR nanoclusters on naïve CD4+ T cells. Collectively, this study suggests a mechanism for increasing T cell functionality to weak TCR stimulation by modulating the membrane protein Flot2, which affects surface TCR clustering. These results may have important implications for improving T cell reactivity in diseases with poor antigenicity, such as anti-tumor immune responses. Citation Format: Sookjin Moon, Peer W. Karmaus, Michael B. Fessler. Flotillin-2 ablation in T cells enhances antigen sensitivity and functionality [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7473.

Development and Validation of an Internet-Based Remote Perimeter (Perimouse).

We sought to validate the feasibility of Perimouse, an internet-based remote perimeter that allows for natural fixation and can be performed on most computers via a web page. In this cross-sectional study, Perimouse evaluated the visual field of 45 healthy people and 27 patients with primary open-angle glaucoma on a laptop. Participants used a mouse cursor to locate new dots on the screen that were determined by preset saccade vectors. A "click and confirm" strategy was used to eliminate the unwanted visual search. Dot brightness was either fixed at 12dB in the suprathreshold program (screening program) or variable in the threshold program. We compared Perimouse outcomes with the Humphrey Field Analyzer (HFA) 24-2 Swedish Interactive Testing Algorithm standard program. In the screening program, Perimouse showed moderate to high concordance with HFA. The intraclass coefficient ranged from 0.58 to 0.86 in different areas of Garway-Heath mapping. In the threshold program, normal subjects had threshold ranging from 19 to 16dB, presenting sensitivity changes according to the "hill of vision". The test-retest difference was 0.09dB. Habitual spectacle correction and environmental luminance (2-337 lux) had little impact on the central or peripheral threshold (P > 0.05). The correlation between Perimouse and HFA threshold sensitivity was strong (R = 0.950), although Perimouse mean defect was 4.40dB higher than the HFA mean defect. Perimouse is a reliable visual field test that correlates strongly with HFA. It shows potential for population screening and monitoring visual field defects. Perimouse assesses the visual field using saccade vectors without eye trackers, enhancing its accessibility via a web page.

Cost-effectiveness of one-year adjuvant trastuzumab therapy in treatment for early-stage breast cancer patients with HER2+ in Vietnam.

In Vietnam, trastuzumab is included in social health insurance's benefits package with a reimbursement rate of 60%, but policymakers have been concerned about its cost-effectiveness. The research aims to evaluate the cost-effectiveness of one-year adjuvant trastuzumab therapy for early-stage breast cancer patients with human epidermal growth receptor 2 (HER2+) from a societal perspective. A Markov model was developed and validated to estimate the lifetime cost and effectiveness (using life year and quality-adjusted life year) of one-year adjuvant trastuzumab therapy compared to chemotherapy (using paclitaxel) alone. Treatment efficacy and transition probabilities were estimated based on published trials (i.e., N9831, NSABP B-31, HERA, and BCIRG 006). Local cost and utility data were employed to capture the Vietnam context. One-way sensitivity analysis, probabilistic sensitivity analysis, threshold, and scenario analysis were also performed. One-year adjuvant trastuzumab therapy combined with chemotherapy compared to chemotherapy alone yielded an additional cost of 888,453,971VND (39,062 US$) with an additional 3.09 LYs and 1.61 QALYs, resulting in an ICER of 287,390,682 VND (12,635 US$) per LY gained, or 519,616,972 VND (22,845 US$) per QALY gained. The ICER exceeds the cost-effective threshold of 1- and 3-time GDP per capita by 6.3 and 2.1 times. The probabilistic sensitivity analysis shows similar results. According to one-way sensitivity analysis, ICERs were driven mainly by transition probabilities and trastuzumab price. One-year adjuvant trastuzumab therapy would be cost-effective at the 3-time GDP per capita threshold if the cost of Herceptin 150mg and 450mg vials were reduced by 56% and 54%, correspondingly. In Vietnam, one-year adjuvant trastuzumab therapy for early-stage breast cancer with HER2+ is not cost-effective. The research provided reliable and updated evidence to support policymakers in revising the health insurance benefit package. The policymakers should consider the options to reduce the cost of trastuzumab (e.g., regarding the use of trastuzumab biosimilars, price negotiation options, and options of optimizing the use of Herceptin vials among concurrent hospitalized breast cancer patients).

Biomechanical Threshold Values for Identifying Clinically Significant Knee-Related Symptoms Six Months Following Anterior Cruciate Ligament Reconstruction.

Slower habitual walking speed and aberrant gait biomechanics are linked to clinically significant knee-related symptoms and articular cartilage composition changes linked to posttraumatic osteoarthritis (PTOA) following anterior cruciate ligament reconstruction (ACLR). To determine specific gait biomechanical variables that can accurately identify individuals with clinically significant knee-related symptoms post-ACLR, and the corresponding threshold values, sensitivity, specificity, and odds ratios for each biomechanical variable. Cross-sectional analysis. Laboratory. Seventy-one individuals (n=38 female; age=21±4 years; height=1.76±0.11 m; mass=75.38±13.79 kg) who were 6 months post-primary unilateral ACLR (6.2±0.4 months). 3D motion capture of 5 overground walking trials was used to calculate discrete gait biomechanical variables of interest during stance phase (1st and 2nd peak vertical ground reaction force [vGRF]; midstance minimum vGRF; peak internal knee abduction and extension moments; and peak knee flexion angle), along with habitual walking speed. Knee Injury and Osteoarthritis Outcome Scores (KOOS) was used to dichotomize patients as symptomatic (n=51) or asymptomatic (n=20) using the Englund et al. 2003 KOOS guidelines for defining clinically significant knee-related symptoms. Separate receiver operating characteristic (ROC) curves and respective areas under the curve (AUC) were used to evaluate the capability of each biomechanical variable of interest for identifying individuals with clinically significant knee-related symptoms. Habitual walking speed (AUC=0.66), vGRF at midstance (AUC=0.69), and 2nd peak vGRF (AUC=0.76), demonstrated low-to-moderate accuracy for identifying individuals with clinically significant knee-related symptoms. Individuals who exhibited habitual walking speeds ≤1.27 m/s, midstance vGRF ≥0.82 BW, and 2nd peak vGRF ≤1.11 BW, demonstrated 3.13, 6.36, and 9.57 times higher odds of experiencing clinically significant knee-related symptoms, respectively. Critical thresholds for gait variables may be utilized to identify individuals with increased odds of clinically significant knee-related symptoms and potential targets for future interventions.

Long-term, non-invasive FTIR detection of low-dose ionizing radiation exposure

Non-invasive methods of detecting radiation exposure show promise to improve upon current approaches to biological dosimetry in ease, speed, and accuracy. Here we developed a pipeline that employs Fourier transform infrared (FTIR) spectroscopy in the mid-infrared spectrum to identify a signature of low dose ionizing radiation exposure in mouse ear pinnae over time. Mice exposed to 0.1 to 2 Gy total body irradiation were repeatedly measured by FTIR at the stratum corneum of the ear pinnae. We found significant discriminative power for all doses and time-points out to 90 days after exposure. Classification accuracy was maximized when testing 14 days after exposure (specificity > 0.9 with a sensitivity threshold of 0.9) and dropped by roughly 30% sensitivity at 90 days. Infrared frequencies point towards biological changes in DNA conformation, lipid oxidation and accumulation and shifts in protein secondary structure. Since only hundreds of samples were used to learn the highly discriminative signature, developing human-relevant diagnostic capabilities is likely feasible and this non-invasive procedure points toward rapid, non-invasive, and reagent-free biodosimetry applications at population scales.

Analysis of the mucosal chemokines CCL28, CXCL14, and CXCL17 in dry eye disease: An in vitro and clinical investigation

Mucosal chemokines have antimicrobial properties and play an important role in mucosal immunity. However, little is known about their expression on the ocular surface. This study aimed to analyze the expression of the mucosal chemokines CCL28, CXCL14 and CXCL17 in corneal and conjunctival epithelial cells under in vitro dry eye (DE) conditions, and in conjunctival samples from healthy subjects and DE patients. Human corneal epithelial cells (HCE) and immortalized human conjunctival epithelial cells (IM-HConEpiC) were incubated under hyperosmolar (400–500 mOsM) or inflammatory (TNF-α 25 ng/mL) conditions for 6 h and 24 h to measure CCL28, CXCL14, and CXCL17 gene expression by RT-PCR and their secretion by immunobead-based analysis (CCL28, CXCL14) and ELISA (CXCL17). Additionally, twenty-seven DE patients and 13 healthy subjects were included in this study. DE-related questionnaires (OSDI, mSIDEQ and NRS) evaluated symptomatology. Ocular surface integrity was assessed using vital staining. Tactile sensitivity was measured with Cochet-Bonnet esthesiometer, and mechanic and thermal (heat and cold) sensitivity using Belmonte's non-contact esthesiometer. Subbasal nerve plexus and dendritic cell density were analyzed by in vivo confocal microscopy. Conjunctival cells from participants were collected by impression cytology to measure mucosal chemokines gene expression by RT-PCR. Our results showed that HCE and IM-HConEpiC cells increased CCL28, CXCL14, and CXCL17 secretion under hyperosmolar conditions. The gene expression of CCL28 was significantly upregulated in conjunctival samples from DE patients. CCL28 expression correlated positively with symptomatology, corneal staining, heat sensitivity threshold, and dendritic cell density. CXCL14 expression correlated positively with age, ocular pain, conjunctival staining, tactile sensitivity, and image reflectivity. CXCL17 expression correlated positively with corneal staining. These results suggest that corneal and conjunctival epithelial cells could be a source of CCL28, CXCL14, and CXCL17 on the ocular surface and that CCL28 might be involved in DE pathogenesis.

Performance Analysis and Clinical Evaluation of an Automated Tool for Plantar Threshold Sensitivity Assessment in a Non-Diabetic Control Population

Abstract Neuropathy is associated with sensation loss in the extremities. Semmes–Weinstein monofilaments are common tools used to assess an individuals' sensation perception. It has long been characterized using hand-applied Semmes–Weinstein monofilaments, however they are subjected to clinician biases and material deviations, and other factors that affect the reproducibility to administer a consistent amount of contact force on the plantar surface. A tool was developed to automate this testing protocol and to more accurately determine an individual's threshold sensitivity at various locations on the plantar surface. Individuals without type 2 diabetes mellitus (DM2) were classed as control subjects. They were evaluated using a hand applied monofilament and the automated tool. The device accuracy of the automated tool was first determined, followed by subject's threshold sensitivity at each location. Twenty-six locations were evaluated per person between 0.35 and 10.0 grams-force. A threshold sensitivity index norm was calculated based on the threshold sensitivity at each location per individual and was plotted against age, body mass index, ankle brachial index, fasting blood sugars, and HbA1c. The device demonstrated accuracy with an absolute error less than or equal to 0.4 grams-force at most locations. Age showed the strongest relationships to sensation loss. As age increased sensitivity to touch decreased. The automated tool was shown to be effective in determining an individual's threshold sensitivity in individuals without DM2. The calculation of the threshold sensitivity index norm was useful to classify sensation loss. The automated tool has the potential to effectively diagnosis neuropathy and document disease progression.

Interventional effect and inflammatory regulation mechanism of dihydroartemisinin combined with pregabalin on neuropathic pain mice

This study aims to clarify the effects of dihydroartemisinin(DHA) combined with pregabalin(PGB) on neuropathic pain(NP) in mice and explore the neuroinflammatory regulatory mechanism. NP mice model was established using spinal nerve ligation, whereas the sham group exposed the spinal nerve without ligation. The mice were randomly divided into sham group, model group, PGB groups of low, medium, and high doses(PGB-L, PGB-M, and PGB-H, with 22, 45, and 91 mg·kg~(-1)), DHA group(16 mg·kg~(-1)), and DHA combined with PGB groups of low, medium, and high doses(DHA + PGB-L, DHA + PGB-M, and DHA + PGB-H). Administration by gavage 18 days after modeling. Von Frey and cold plate were used to detect mechanical pain threshold and cold pain sensitivity in mice. The tail suspension test and forced swimming test were used to investigate depressive behavior, and the open field test was used to estimate anxiety behavior. The Morris water maze was used to evaluate cognitive function. Liquid suspension chip technology was used to quantitatively analyze immune inflammation-related factors. Immunofluorescence was used to detect the expression of CC chemokine ligand 3(CCL3) and transmembrane protein 119(TMEM119). The results showed that compared with the sham group, the mechanical pain and cold pain sensitivity thresholds of the model group were significantly reduced, and the struggle time was significantly increased in the tail suspension test and forced swimming test. The activity time in the central area was significantly reduced in the open field test. The residence time in the second/fourth quadrant was significantly longer than that in other quadrants, and the latency time of platform climbing significantly increased after platform withdrawal in the Morris water maze experiment. The expression of CCL3 was significantly increased; the number of TMEM119 positive cells and the cell body area were significantly increased. Compared with the model group, the DHA + PGB-M group showed a significant increase in mechanical pain and cold pain sensitivity thresholds, as well as a significant increase in struggle time in the tail suspension test and forced swimming test. The activity time in the central area of the open field test was significantly reduced. The residence time in the second/fourth quadrant was significantly shorter than that in other quadrants, and the latency time of platform climbing after platform withdrawal was significantly reduced. Compared with the PGB-M group, the mechanical pain threshold of D14-17 in the DHA + PGB-M group was significantly increased, and the struggle time during forced swimming was significantly increased. The residence time in the second/fourth quadrant of the Morris water maze was significantly shorter than that in other quadrants. Compared with the model group, the expression of CCL3, the number of TMEM119 positive cells, and the cell body area in the DHA + PGB-M group were significantly decreased. This study indicates that DHA + PGB can enhance the analgesic effect of PGB on NP mice, break through the limitations of PGB tolerance, and make up for the shortcomings of PGB in antidepressant and cognitive improvement. Its mechanism may be related to regulating neuroinflammation by inhibiting the activation of microglial cells and expression of CCL3.

The Case of the Missing Very High-energy Gamma-Ray Bursts: A Retrospective Study of Swift Gamma-Ray Bursts with Imaging Atmospheric Cherenkov Telescopes

Gamma-ray bursts (GRBs) are particle acceleration sites that can emit photons in the very high-energy (VHE) domain through nonthermal processes. From 2004 until 2018, the current generation of Imaging Atmospheric Cherenkov Telescopes (IACTs) did not detect any GRB in the VHE domain. However, from 2018 to 2020, five detections were reported. In this work, we try to solve the case of the missing VHE GBRs prior to 2018. We aim to identify GRBs that might have eluded VHE detection in past years by the H.E.S.S., MAGIC, and VERITAS IACTs. To do so, we study GRBs with known redshift detected by Swift from 2004 until June 2022. We first identify all GRBs that could have been observed by these IACTs since 2004, considering observation conditions and visibility constraints. We assume a relation between the X-rays and the VHE gamma rays based on the VHE GRBs detected to date and combine this with the redshift measurements, instrument response information, and observation conditions to predict the observed VHE gamma-ray flux from the Swift X-Ray Telescope measurements. We report findings on 12 bright low-redshift GRBs that we identify as most likely to have been detected in the VHE domain by current IACTs. The rate of IACT-detectable GRBs with ideal observation conditions is <1 VHE GRB per year with the current configuration. With its lower energy threshold and higher sensitivity, this rate increases to ∼4 VHE GRBs per year with the Cherenkov Telescope Array.

Age-related changes in gap detection thresholds in adult cochlear-implant users: Effects of stimulus level and electrode-to-neural interface

Aging is associated with reduced sensitivity to brief temporal gaps in auditory stimuli. Although gap detection is a relative strength among late-deafened cochlear-implant users, aging and electrode-to-neural interface (ENI) factors may contribute to temporal processing difficulties. Because aging may negatively impact perception particularly at very low and very high input levels, we hypothesized larger gap detection thresholds (GDTs) at poor-ENI electrodes and an interaction between age and level such that GDT improvement with increased level would be less evident in older listeners. GDTs were measured on three electrodes selected to span a range of good-to-poor ENI based on electrically-evoked compound action potential amplitude growth or threshold sensitivity to increased pulse rate. GDTs were assessed using constant-amplitude single-electrode 1000-pps pulse trains presented at 40/60/80/100% dynamic range. In preliminary data (N = 4), GDTs averaged 3 ms at 100%DR and 40 ms at 40%DR. Listeners with better average ENI metrics displayed better GDTs. Within-subject, an advantage for best-ENI electrode over poorer-ENI electrodes was evident only at low levels. Finding an interaction between age and level such that temporal processing is impaired at both low and high (but not mid) levels for older listeners may help elucidate the contributions of peripheral versus central factors.

Vertical Evolution of Ozone Formation Sensitivity Based on Synchronous Vertical Observations of Ozone and Proxies for Its Precursors: Implications for Ozone Pollution Prevention Strategies.

Photochemical ozone (O3) formation in the atmospheric boundary layer occurs at both the surface and elevated altitudes. Therefore, the O3 formation sensitivity is needed to be evaluated at different altitudes before formulating an effective O3 pollution prevention and control strategy. Herein, we explore the vertical evolution of O3 formation sensitivity via synchronous observations of the vertical profiles of O3 and proxies for its precursors, formaldehyde (HCHO) and nitrogen dioxide (NO2), using multi-axis differential optical absorption spectroscopy (MAX-DOAS) in urban areas of the Beijing-Tianjin-Hebei (BTH), Yangtze River Delta (YRD), and Pearl River Delta (PRD) regions in China. The sensitivity thresholds indicated by the HCHO/NO2 ratio (FNR) varied with altitude. The VOC-limited regime dominated at the ground level, whereas the contribution of the NOx-limited regime increased with altitude, particularly on heavily polluted days. The NOx-limited and transition regimes played more important roles throughout the entire boundary layer than at the surface. The feasibility of extreme NOx reduction to mitigate the extent of the O3 pollution was evaluated using the FNR-O3 curve. Based on the surface sensitivity, the critical NOx reduction percentage for the transition from a VOC-limited to a NOx-limited regime is 45-72%, which will decrease to 27-61% when vertical evolution is considered. With the combined effects of clean air action and carbon neutrality, O3 pollution in the YRD and PRD regions will transition to the NOx-limited regime before 2030 and be mitigated with further NOx reduction.

Quantitative mass spectrometry with ¹⁸O labelling as an alternative approach for determining protease activity: an example of trypsin

SCIENTIFIC RELEVANCE. In the quality control of proteolytic enzyme components of medicinal products, the activity of proteases is determined by spectrophotometry, which involves mea­suring the amidase or esterase activity using a synthetic substrate and the proteolytic activity using the Anson method. These methods require special substrates and have low sensitivity; their specificity may be insufficient, which may lead to serious errors. Quantitative mass spectrometry is an alternative approach to protease activity assays, which involves adding an isotope-labelled peptide to hydrolysates of the test enzyme. This approach allows determining the activity of proteases, notably, by the hydrolysis of specific peptide bonds, while simulta­neously confirming the identity and specificity of the test sample. Quantitative mass spectrometry has high sensitivity and does not require special substrates.AIM. This study aimed to investigate the possibility of enzymatic activity assay and enzyme identification by quantitative mass spectrometry with ¹⁸O labelling through an example of trypsin with casein.MATERIALS AND METHODS. The study used trypsin, casein, and H₂¹⁸O (Izotop, Russia). Peptide separation was performed using an Agilent 1100 HPLC system; mass spectra were obtained using a Bruker Ultraflex II MALDI-TOF/TOF mass spectrometer. Quantitative mass spectrometry was performed using a standard peptide, which was obtained from casein by tryptic digestion and HPLC purification. For ¹⁸O labelling, the authors dried the peptide and incubated it in H₂¹⁸О water. The quantitative analysis of the product was carried out using MALDI-TOF mass spectrometry. The authors used quantitative mass spectrometry with ¹⁸O labelling to determine enzymatic activity and calculate the Michaelis constant (KM).RESULTS. Following the tryptic digestion of casein, the authors identified the fragments corre­sponding to casein chains. The authors produced the isotope-labelled standard peptide and calculated its concentration using mass spectrometry. The authors determined the rate of casein digestion by trypsin and calculated the KM for trypsin, which was 13.65±0.60 μM. The standard deviation for repeated measurements showed that the mass-spectrometric method had a lower error of measurement than the spectrophotometric method. The sensitivity threshold for the mass-spectrometric method was 0.50±0.08 μM.CONCLUSIONS. The results obtained with trypsin confirm the possibility of enzymatic activity determination by the proposed method of quantitative mass spectrometry with ¹⁸O labelling. According to the sensitivity evaluation results, this method can be used for the simultaneous determination of enzyme activity, identity, and specificity. The proposed mass spectrometry approach is universal, it does not require expensive materials and reagents, and it can be easily adapted to determine the activity of virtually any protease.

Thresholds and extent of temperature effects on maize yield differ in different grain-filling stages

Temperature is a vital environmental factor affecting grain filling and maize yield. The response of maize yield to temperature at different stages of grain filling, however, remains uncharacterized. This study used “Zhengdan 958” as the test material to analyze the high-temperature threshold and yield sensitivity of grain-filling in different periods without water stress by using the data from staging sowing experiments at agro-meteorological experimental stations in Hebi and Suzhou in the Huang-Huai-Hai Plain from 2019 to 2022. The results demonstrated that: (1) the maximum temperature threshold was different in various periods of maize grain-filling in the Huang-Huai-Hai Plain, showing the early grain-filling period (EP) > the active grain-filling period (AP) > the late grain-filling period (LP). With the largest differences in temperature thresholds found in AP, the maximum temperature threshold of AP can better reflect the characteristics of grain filling rather than the whole filling period. (2) The heat of the grain-filling period can explain more than 80 % of the yield variation and affect the yield by influencing the number of days required to reach the maximum grain-filling rate (Vmaxd) and the duration of the active grain-filling period (DAP). (3) The growing degree days (GDD) is the most significant controlling factor affecting yield; however, the effect of heat degree days (HDD) cannot be ignored. The HDD and cumulative thresholds of HDD in the EP and AP of grain-filling can better reflect the effect of heat on yield. The accumulation thresholds of HDD at Hebi and Suzhou were 28.1 °C·d and 15.2 °C·d in the EP period, and 31.0 °C·d and 14.9 °C·d in the AP period, respectively. The results provide a basis for the precise identification of heat disasters during grain-filling and the scientific adjustment of sowing dates.

Heat stress memory differentially regulates the expression of nitrogen transporter genes in the filamentous red alga 'Bangia' sp. ESS1.

To withstand high temperatures that would be lethal to a plant in the naïve state, land plants must establish heat stress memory. The acquisition of heat stress tolerance via heat stress memory in algae has only been observed in the red alga 'Bangia' sp. ESS1. In this study, we further evaluated the intrinsic ability of this alga to establish heat stress memory by monitoring hydrogen peroxide (H2O2) production and examining the relationship between heat stress memory and the expression of genes encoding nitrogen transporters, since heat stress generally reduces nitrogen absorption. Next, genes encoding nitrogen transporters were selected from our unpublished transcriptome data of 'Bangia' sp. ESS1. We observed a reduction in H2O2 content when heat stress memory was established in the alga. In addition, six ammonium transporter genes, a single-copy nitrate transporter gene and two urea transporter genes were identified. Two of these nitrogen transporter genes were induced by heat stress but not by heat stress memory, two genes showed heat stress memory-dependent expression, and one gene was induced by both treatments. Heat stress memory therefore differentially regulated the expression of the nitrogen transporter genes by reducing heat stress-inducible gene expression and inducing heat stress memory-dependent gene expression. These findings point to the functional diversity of nitrogen transporter genes, which play different roles under various heat stress conditions. The characteristic effects of heat stress memory on the expression of individual nitrogen transporter genes might represent an indispensable strategy for reducing the threshold of sensitivity to recurrent high-temperature conditions and for maintaining nitrogen absorption under such conditions in 'Bangia' sp. ESS1.

Forest aboveground biomass estimation by GEDI and multi-source EO data fusion over Indian forest

ABSTRACT Monitoring changes in carbon stocks through forest biomass assessment is crucial for carbon cycle studies. However, challenges in obtaining timely and reliable ground measurements hinder creation of the spatially continuous maps of forest aboveground biomass density (AGBD). This study proposes an approach for generating spatially continuous maps of forest aboveground biomass density (AGBD) by combining Global Ecosystem Dynamics Investigation (GEDI) LiDAR-based data with open-access earth observation (EO) data. The key contribution of the study lies in the systematic evaluation of various model configurations to select the optimal model for AGBD generation. The evaluation considered various model configurations, including predictor sets, spatial resolution, beam selection, and sensitivity thresholds. We used a Random Forest model, trained through five-fold cross-validation on 80% of the total data, to estimate AGBD in the Indian forest region. Model performance was assessed using the 20% independent test dataset. Results, using Sentinel-1 and 2 predictors, yielded R2 values of 0.55 to 0.60 and RMSE of 48.5 to 56.3 Mg/ha. Incorporating forest and agroclimatic zone attributes improved performance (R2: 0.59 to 0.69, RMSE: 42.2 to 53.3 Mg/ha). The selection of the top 15 predictors, which favoured features from Sentinel-2, DEM, forest attributes, and agroclimatic zones, and GEDI data with sensitivity >0.98, yielded the optimal model with an R2 of 0.64 and RMSE of 46.59 Mg/ha. The results underscore the significance of incorporating attributes like forest and agro-climatic zones and the need for an optimal model selection considering predictor types and GEDI shot characteristics. The top-performing model is validated in Simdega, Jharkhand (R2: 0.74, RMSE: 39.3 Mg/ha), demonstrating the methodological potential of this approach. Overall, this study emphasizes the methodological prospects of integrating multi-source open-access EO data to produce spatially continuous aboveground biomass (AGB) maps through data fusion.

Abstract WP190: Comparison of Collateral Score to ASPECTS to Exclude "Very Large" Infarct Core Volumes in Anterior Circulation Large Vessel Occlusion Strokes at 0-24 Hours

Purpose: ASPECTS&lt;3 was an explicit exclusion criterion in the SELECT2 trial to exclude "very large" infarcts (&gt;100mL) for reperfusion using endovascular thrombectomy (EVT). While specific, ASPECTS&lt;3 may be too insensitive of a threshold on noncontrast CT at 0-24 hours (especially 0-6 hours). We aim to determine if CTA based Collateral Score (CS) can be a more sensitive surrogate marker for infarct core volume (ICV)&gt;100mL while maintaining similar specificity to ASPECTS. Methods: Retrospective analysis included consecutive stroke patients arriving within 24 hours of onset, with intracranial ICA and/or M1 occlusion on CTA, and had concurrent CT perfusion. RAPID AI software estimated ICV using the rCBF&lt;30% threshold. CS was scored on CTA using the method of Tan et al on a 4-point scale for % collaterals compared to contralateral side: 0 none, 1 &gt;0 but &lt;50%, 2 &gt;=50 but &lt;100%, and 3 100%. ROC curve analysis was used to find the optimal CS cutpoint with high specificity for ICV&gt;100mL. Sensitivity and specificity of that CS threshold vs ASPECTS&lt;3 were compared using the N-1 chi square test. Results: 164 patients were included with median (IQR) age of 74 (66-84), NIHSS of 20 (12-25), and time of onset-to-CT of 4 hours (2-7.5). The LVOs were 17 ICA (10.4%), 108 M1 (65.9%), and 39 both (23.8%), with median ICV of 12mL (0-45). 16 patients had ICV&gt;100mL (9.8%) with median of 136mL (105-172). Using ASPECTS&lt;3 identified only 1 of these (ICV of 118mL at 18.5 hours), sensitivity of 6.3% (95% CI: 0.16-30.2%), with no false positives, specificity of 100% (95% CI: 97.6-100%). ROC analysis for CS showed AUC=0.818 (p&lt;0.001), with maximal specificity at CS=0 (no visible collaterals). Using CS=0 identified 6 of these infarcts, sensitivity of 37.5% [95% CI: 15.2-64.6%], with 2 false positives, specificity of 98.7% [95% CI: 95.2-99.8%]. The 2 false positives were ICV of 97mL at 2 hours and 96mL at 3 hours. The improved sensitivity of CS=0 over ASPECTS&lt;3 was significant (p=0.036) while the difference in specificity was not (p=0.144). Conclusion: In our cohort of LVOs, CS=0 was a more sensitive surrogate marker for ICV&gt;100mL compared to ASPECTS&lt;3 while maintaining near 100% specificity. If confirmed in future prospective studies, CS=0 has the potential to further streamline patient selection for EVT.

Objective Outcomes to Evaluate Voretigene Neparvovec Treatment Effects in Clinical Practice

AimTo assess the efficacy of Voretigene Neparvovec (VN) treatment by objective fixation stability and chromatic pupillometry testing in clinical practice. DesignRetrospective cohort study with longitudinal follow-up. SubjectsTwelve patients (aged 7 to 34 years) with RPE65-related inherited retinal dystrophies were treated at the same center with VN in both eyes. MethodsPatients treated at the same center with VN were evaluated over a 12-month post-treatment follow-up by subjective and objective tests. Furthermore, patients treated with VN who developed atrophy were compared to those who did not. Main outcome measuresBest corrected visual acuity (BCVA), full field stimulus threshold test (FST), semi-automated kinetic visual field (SKVF), microperimetry, and chromatic pupillometry over a 12-month follow-up ResultsSignificant improvements of BCVA (p<0.001), SKVF (p<0.05) and FST (p<0.001) were already observed 45 days after treatment and were maintained at the 12-month timepoint. Fixation stability, assessed by microperimetry, improved significantly (p<0.05) after treatment. Chromatic pupillometry showed significant improvements (p<0.05) at the 6- and 12-month timepoints. The increase in maximum pupillary constriction significantly (p<0.001) correlated with higher retinal sensitivity in FST. Four patients developed multifocal retinal atrophy in both eyes, detected at the 6-month timepoint, but this atrophy was not generally associated with worse visual function outcomes. ConclusionsThis study is the first attempt to demonstrate the efficacy of VN treatment in real life using objective tests in addition to those normally performed in clinical practice. Our findings show a significant improvement of retinal function both in subjective assessments, such as BCVA, SKVF and FST, and in objective measurements of fixation stability and maximum pupillary constriction. Moreover, the significant correlation between maximum pupillary constriction and light sensitivity thresholds corroborates the introduction of chromatic pupillometry as an objective test to better assess treatment outcomes in patients with inherited retinal dystrophies.