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235 citation(s) found for "Shepherd, LE".

Esophageal lymphocytosis: exploring the knowns and unknowns of this pattern of esophageal injury
Coady, Laoise, Sheahan, Kieran , Brown, Ian , Gill, Anthony J. , Kumarasinghe, Priyanthi , Kushima, Ryoji , Lauwers, Gregory Y. , Pai, Rish K. , Shepherd, Neil A. , Slavík, Tomáš , Langner, Cord , Brown, Ian S , Carneiro, Fátima , Srivastava, Amitabh

Mayo Clinic

Expert Review of Gastroenterology & Hepatology | September 13, 2024 | Volume: 18 | Issue: 9 | Pages: 529-539

10.1080/17474124.2024.2385493 | PMID 39268773 Get It

Global retrospective study comparing consolidation ALK tyrosine kinase inhibitors (TKI) to durvalumab (durva) or observation (obs) after chemoradiation (CRT) in unresectable locally-advanced ALK+ non-small cell lung cancer (NSCLC).
Jayakrishnan, Ritujith, Lin, Jessica Jiyeong, Shakya, Purnima, Dilling, Thomas J. , Grohé, Christian , Fitzgerald, Bailey G. , Adib, Elio , Neal, Joel W. , Whitaker, Ryan, Mañana, Ana I. Velazquez, Goldberg, Sarah B. , Nassar, Amin H. , Shepherd, Frances Alice , Lin, Jessica Jiyeong, Lin, Steven H. , Bar, Jair , Gupta, Shruti , Sankar, K. Nathan , Yu, Helena Alexandra , Naqash, Abdul Rafeh , Kim, So Yeon

Mayo Clinic

Journal of Clinical Oncology | June 26, 2024 | Volume: 42 | Issue: 16_suppl | Pages: 8013-8013

10.1200/jco.2024.42.16_suppl.8013 Get It

8013 Background: For patients (pts) with unresectable locally-advanced NSCLC, standard of care involves durva consolidation after concurrent CRT, although its benefit in ALK+ tumors is unclear. The ALINA trial demonstrated adjuvant efficacy of alectinib in resected ALK+ NSCLC, but the optimal consolidation strategy for unresectable locally-advanced ALK+ NSCLC remains elusive. Methods: This multi-institutional international retrospective analysis included pts with stage III unresectable ALK+ NSCLC who received an ALK TKI, durva, or obs alone after concurrent CRT between 2015-2022. Baseline characteristics of age, sex, smoking history, and PD-L1 status were collected. Clinical outcomes including real-world progression-free survival (rw-PFS), overall survival (OS), and treatment-related adverse events (trAE) as defined using CTCAE 5.0 were assessed, and multivariate cox regression models were performed. Results: Sixty-four pts across 16 institutions were included. The median age was 57 (IQR 49-66) and 61% were females. The majority had adenocarcinoma (97%) and had never smoked (58%). 15 received ALK TKI (10 alectinib, 3 crizotinib, 1 brigatinib, 1 lorlatinib), 30 received durva, and 19 received obs alone. There was no significant difference in stage of cancer (IIIA, B, or C) or PD-L1 status among groups. After adjusting for stage and age at CRT initiation, median rw-PFS was significantly longer for ALK TKI (rw-PFS not reached [NR], 95% CI 22.7-NR) vs durva (11.3 months (mo), 95% CI 9.2-18.5, p= 0.005, HR = 0.12) or obs (7.4 mo, 95% CI 3.4-12.5, p < 0.0001). Two (13%) pts progressed on ALK TKI. 25 pts (83%) progressed on durva leading to treatment with ALK TKI in 23, and 18 (95%) progressed while under obs leading to treatment with ALK TKI in 15. 3-year OS was 100% for ALK TKI vs 90.5% for durva vs 63.5% for obs. Median OS was NR (95% CI NR-NR) for both ALK TKI and durva vs 70.6 mo (24.9-NR) in the obs group ( p= 0.03 for both ALK TKI and durva compared to obs). Median duration of therapy was 24.7 mo with ALK TKI and 6.5 mo with durva. Grade ≥3 trAE occurred in 27%, 7%, 6% of pts treated with ALK TKI (1 fatigue, 1 diarrhea, 1 hyperbilirubinemia, 1 pneumonitis), durva (1 fatigue, 1 neutropenia), and obs (1 neutropenia) respectively. Treatment discontinuation due to toxicity occurred in 4 (27%) with ALK TKI and in 3 (10%) with durva. Conclusions: In this retrospective study of stage III ALK+ NSCLC, consolidation ALK TKI demonstrated clinically meaningful improvement in PFS and OS over durva and obs, while showing a slightly higher rate of trAE over dura and obs. Furthermore, we show a high rate of progression following CRT alone in ALK+ NSCLC. These findings underscore the need for prospective molecularly driven trials to determine the optimal consolidation therapy for unresectable ALK+ NSCLC.
Adjunctive Statistical Standardization of Adjuvant Estrogen Receptor and Progesterone Receptor in Canadian Cancer Trials Group MA.27 Postmenopausal Breast Cancer Trial of Exemestane Versus Anastrozole
Chapman, Judith‐Anne W. , Bayani, Jane , Sengupta, Sandip , Bartlett, John M.S. , Quintayo, Mary Anne , Virk, Shakeel , Goss, Paul E., Ingle, James N. , Ellis, Matthew J. , Budd, G. Thomas , Ansari, Rafat , Tozer, Richard , D’Souza, David , Chalchal, Haji , Spadafora, Silvana , Stearns, Vered , Perez, Edith A. , Whelan, Timothy J., Elliott, Catherine, Shepherd, Lois E. , Taylor, Karen J. , Whelan, Timothy J. , Ingle, J , Virk, Shakeel , Ellis, Matthew J , Sledge, George W , Budd, G Thomas , Rabaglio-Poretti, Manuela , Stearns, Vered , Perez, Edith A , Gelmon, Karen A , Whelan, Timothy J , Shepherd, LE , Chen, Bingshu E , Taylor, Karen J , Piper, Tammy , Sledge, George W. , Rabaglio, Manuela , Gelmon, Karen A. , Chen, Bingshu E.

Mayo Clinic

Journal of Clinical Oncology | June 2, 2024 | Volume: 42 | Issue: 24 | Pages: 2887-2898

10.1200/jco.24.00835 | PMID 38824432 Get It

PURPOSE ASCO/College of American Pathologists guidelines recommend reporting estrogen receptor (ER) and progesterone receptor (PgR) as positive with (1%-100%) staining. Statistically standardized quantitated positivity could indicate differential associations of positivity with breast cancer outcomes. METHODS MA.27 (ClinicalTrials.gov identifier: NCT00066573 ) was a phase III adjuvant trial of exemestane versus anastrozole in postmenopausal women with early-stage breast cancer. Immunochemistry ER and PgR HSCORE and % positivity (%+) were centrally assessed by machine image quantitation and statistically standardized to mean 0 and standard deviation (SD) 1 after Box-Cox variance stabilization transformations of square for ER; for PgR, (1) natural logarithm (0.1 added to 0 HSCOREs and 0%+) and (2) square root. Our primary end point was MA.27 distant disease-free survival (DDFS) at a median 4.1-year follow-up, and secondary end point was event-free survival (EFS). Univariate survival with cut points at SDs about a mean of 0 (≤–1; (–1, 0]; (0, 1]; >1) was described with Kaplan-Meier plots and examined with Wilcoxon (Peto-Prentice) test statistic. Adjusted Cox multivariable regressions had two-sided Wald tests and nominal significance P < .05. RESULTS Of 7,576 women accrued, 3,048 women's tumors had machine-quantitated image analysis results: 2,900 (95%) for ER, 2,726 (89%) for PgR, and 2,582 (85% of 3,048) with both ER and PgR. Higher statistically standardized ER and PgR HSCORE and %+ were associated with better univariate DDFS and EFS ( P < .001). In multivariable assessments, ER HSCORE and %+ were not significantly associated ( P = .52-.88) with DDFS in models with PgR, whereas higher PgR HSCORE and %+ were significantly associated with better DDFS ( P = .001) in models with ER. CONCLUSION Adjunctive statistical standardization differentiated quantitated levels of ER and PgR. Patients with higher ER- and PgR-standardized units had superior DDFS compared with those with HSCOREs and %+ ≤–1.
Adjunctive statistical standardization of quantitated adjuvant ER and PgR in CCTG MA.27.
Chapman, Judy‐Anne W., Bayani, Jane , Sengupta, Sandip , Battlett, John MS, Quintayo, Mary Anne , Virk, Shakeel , Goss, Paul E., Budd, G. Thomas , Perez, Edith A. , Whelan, Timothy J. , Shepherd, L. E., Piper, Tammy , Ingle, James N. , Ellis, Matthew J. , Sledge, George W. , Rabaglio, Manuela , Stearns, Vered , Gelmon, Karen A. , Chen, Bingshu E. , Taylor, Karen J.

Mayo Clinic

Journal of Clinical Oncology | May 29, 2024 | Volume: 42 | Issue: 16_suppl | Pages: 567-567

10.1200/jco.2024.42.16_suppl.567 Get It

567 Background: We proposed adjunctive statistical standardization of quantitated ER and PgR to improve inter-laboratory comparability of biomarker results and therapeutic management of breast cancer. Methods: We utilized CCTG MA.27 (NCT00066573), an adjuvant phase III trial of exemestane versus anastrozole in postmenopausal women with ER+ and/or PgR+ tumours. IHC ER and PgR HSCORE and % positivity (%+) were centrally assessed by machine image quantitation, and each statistically standardized to mean of 0, standard deviation of 1 following Box-Cox variance stabilization transformations of square for ER; for PgR, 1.) natural logarithm (0.1 added to 0 HSCOREs and 0 %+), 2.) square root. The primary endpoint was STEEP distant disease-free survival (DDFS) at the longest trial follow-up of median 4.1 years; a secondary endpoint was event-free survival (EFS). Survival was described with Kaplan-Meier plots and tested with the univariate Wilcoxon (Peto-Prentice) test statistic. We examined cut-points at standard deviations about mean of 0 (<-1; (-1,0]; (0,1]; >1) and explored single cut-points. Cox multivariate regressions were adjusted for age, T and N stage, grade, lymphovascular invasion, treatment, and baseline patient demographics; 2-sided Wald tests had nominal significance if p<0.05. Results: Of the 7576 women accrued, 3048 women had machine-quantitated image analysis results: 2900 (95%) for ER; 2726 (89%) for PgR. Statistically standardized HSCORE and %+ units differentiated both univariate DDFS and EFS; DDFS was significantly different by ER levels (p<0.001) and PgR levels (p<0.001). In multivariable assessments, ER HSCORE and %+ were not significantly associated (p=0.52-0.88) with the DDFS primary endpoint in models with PgR, while higher PgR HSCORE and %+ had significantly better DDFS (p=.001, in all instances) in models with ER. Conclusions: DDFS was superior for patients with higher ER and PgR standardized units compared with those with HSCOREs and %+ <-1. The adjunctive statistical standardization of ER and PgR performed here is similar to that mandated for clinical practice by the World Health Organization for BMD. [Table: see text]
Abstract PO3-02-05: Racial and Ethnic Differences in Clinical Outcomes among North American Patients with Hormone Receptor-Positive, HER2-negative, Early Breast Cancer in the PALLAS Trial (AFT-05)
Kantor, Olga , Dueck, Amylou, Burstein, Harold J. , Shepherd, Lois E. , Hahn, Olwen, Anderson, D. Mark , Rugo, Hope, Dayao, Zoneddy , Clifton, Katherine , Lu, Dongrui R. , O’Brien, Patrick, Scovil, Sara, Fayanju, Oluwadamilola M. , Dueck, Amylou C. , Gnant, Michael , Goetz, Matthew P. , Isaacs, Claudine , Anderson, Daniel, Miller, Kathy D. , Traina, Tiffany A , Clifton, Katherine , Winer, Eric P. , Wolff, Antonio C. , Wolmark, Norman , DeMichele, Angela , Mayer, Erica L.

Mayo Clinic

Cancer Research | May 2, 2024 | Volume: 84 | Issue: 9_Supplement | Pages: PO3-02-05-PO3-02-05

10.1158/1538-7445.sabcs23-po3-02-05 Get It

Abstract Introduction: Analyses of multiple clinical trials have suggested racial and ethnic disparities in outcomes for early-stage, hormone receptor-positive and HER2-negative (HR+HER2-) breast cancer, however, none of these studies examined the use of adjuvant CDK4/6 inhibitors. The objective of this study was to explore racial and ethnic differences in toxicity, treatment duration, and disease outcomes in patients (pts) with early-stage HR+HER2- breast cancer treated with or without adjuvant palbociclib on the PALLAS trial. Methods: The PALLAS phase III, global, open-label trial randomized 5,796 pts with stage II-III HR+HER2- breast cancer to 2 years of palbociclib plus ongoing provider/patient choice adjuvant endocrine therapy (ET+palbo) vs. ET alone (ET). The analytic cohort was limited to pts enrolled in North America with known self-reported race and ethnicity (Non-Hispanic White, Non-Hispanic Black, Hispanic, Asian or Pacific Islander). Descriptive statistics were used to examine treatment characteristics, early discontinuation, and toxicity by race and ethnicity. Kaplan-Meier curves were used to estimate 3-year locoregional recurrence-free survival (LRFS) and invasive disease-free survival (IDFS) stratified by racial and ethnic group. Cox proportional hazards models were used identify predictors of LRFS and IDFS. Results: 2,547 North American pts were randomized and included in the intent-to-treat population with a median follow-up of 59.8 months; 1,996 (78.4%) identified as Non-Hispanic White (NHW), 132 (5.2%) Non-Hispanic Black (NHB), 156 (6.1%) Hispanic, and 134 (5.3%) Asian or Pacific Islander (API). Stage, performance status, type of surgery, and prior radiation were similar across racial and ethnic groups. Age, body mass index, grade, and prior chemotherapy differed by race and ethnicity (p&lt; 0.05). Median age was lowest in API pts and highest in NHW pts (47.5 vs 53.0 years, respectively). Median body mass index was lowest in API and highest in NHB pts (24.4 vs 30.9). NHB pts were most likely to have high-grade disease (40.9% vs 26.9-30.5% in other groups). NHW pts were least likely to have received prior chemotherapy (81.0% vs 87.1-91.0%). Palbociclib early discontinuation was lowest in NHB pts (50.7%) and highest in Hispanic pts (65.9%), p=0.14. ET early discontinuation was similar across all groups (p=0.35). Palbociclib grade 3-4 overall toxicity was variable across groups (NHW 71.6%, NHB 79.1%, Hispanic 69.5%, API 85.2%), but this variation did not reach statistical significance (p=0.07). Neutropenia was highest in API pts (90.0% vs 57.3% in NHW, 58.2% in NHB, and 51.2% in Hispanic pts, p&lt; 0.01). Overall 3-year LRFS was 98% (95% CI 97-98%) and IDFS was 89% (95% CI 88-90%). LRFS and IDFS were statistically similar by race and ethnicity and within each study arm (Table). No differences in LRFS or IDFS were seen by race or ethnicity in adjusted models (p=0.95). Conclusions: In this clinical trial population of HR+HER2- breast cancer patients exposed to similar treatments, no racial/ethnic differences were seen in short-term LRFS or IDFS across study arms. Differences in palbociclib toxicity by racial and ethnic group, particularly neutropenia, were seen with the highest toxicity in API patients; however, this difference did not translate into early discontinuation of palbociclib or ET. Table: 3-year Kaplan-Meier Survival Outcomes Stratified by Race and Ethnicity Citation Format: Olga Kantor, Oluwadamilola (Lola) Fayanju, Amylou Dueck, Michael Gnant, Harold Burstein, Matthew Goetz, Claudine Isaacs, Lois Shepherd, Olwen Hahn, Daniel Anderson, Kathy Miller, Hope Rugo, Tiffany Traina, Zoneddy Dayao, Katherine Clifton, Eric Winer, Antonio Wolff, Norman Wolmark, Dongrui Lu, Patrick O'Brien, Sara Scovil, Angela DeMichele, Erica Mayer. Racial and Ethnic Differences in Clinical Outcomes among North American Patients with Hormone Receptor-Positive, HER2-negative, Early Breast Cancer in the PALLAS Trial (AFT-05) [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-02-05.
Abstract PO1-27-10: Adjunctive statistical standardization of quantitated machine image analysis of Estrogen and Progesterone Receptors: CCTG MA.27 trial
Chapman, Judy-Anne, Bayani, Jane , Sengupta, Sandip , Bartlett, John M.S. , Quintayo, Mary Anne , Virk, Shakeel , Goss, Paul E. , Budd, G. Thomas , Ansari, Rafat , Tozer, Richard , D’Souza, David , Chalchal, Haji , Spadafora, Silvana , Perez, Edith A. , Gelmon, Karen, Whelan, Timothy J. , Elliott, Catherine, Shepherd, L. E., Chapman, Judy‐Anne W., Piper, Tammy , Ingle, James N. , Ellis, Matthew J. , Sledge, George W. , Rabaglio, Manuela , Stearns, Vered , Chen, Bingshu E. , Taylor, Karen J.

Mayo Clinic

Cancer Research | May 2, 2024 | Volume: 84 | Issue: 9_Supplement | Pages: PO1-27-10-PO1-27-10

10.1158/1538-7445.sabcs23-po1-27-10 Get It

Abstract Background: Adjuvant breast cancer therapy is informed by whether a tumour is positive or negative for the biomarkers ER, PgR, and HER2, often without regard to level of positivity. Quantitation has been proposed to improve therapeutic management. Adjunctive statistical standardization has been proposed to improve inter-laboratory comparability of biomarkers results. Methods: This primary report utilized adjunctive statistical standardization of machine-quantitated image analysis biomarker assessments. CCTG MA.27 (NCT00066573) is an adjuvant phase III trial of exemestane versus anastrozole in postmenopausal women with ER+ and/or PgR+ tumours. IHC ER, PgR, and HER2 were centrally assessed, with FISH (HER2;HER2/CEP17) determinations for equivocal IHC HER2. HSCOREs were statistically standardized to a mean of 0, standard deviation of 1 following Box-Cox variance stabilization transformations of square for ER and natural logarithm for PgR (0.1 was added to 0 HSCOREs). The primary endpoint was STEEP distant disease-free survival (DDFS) at the longest trial follow-up of median 4.1 years. Survival was described with Kaplan-Meier plots. The univariate Wilcoxon (Peto-Prentice) test statistic was used with usual designation of negative/positive (0; &gt;0), and standardized cut-points at standard deviations about mean of 0(&lt;-1; (-1,0]; (0,1]; &gt;1). Cox multivariate regressions adjusted for age, T and N stage, grade, lymphovascular invasion, treatment, and baseline patient demographics, utilized likelihood ratio tests. Nominal significance was p=0.05. Results: Of the 7576 women accrued, 3048 had machine-quantitated image analysis results: 2900 (95%) for ER; 2726 (89%) for PgR. Only 8 women were ASCO/CAP ER- (HSCORE 0); PgR HSCORE was 0 for 533. Statistically standardized units differentiated DDFS ER levels (p&lt; 0.001) and PgR levels (p&lt; 0.001). In adjusted multivariate analyses, higher ER HSCORE was associated with better DDFS (p=0.05) with weak evidence of an association (p=0.11) for standardized HSCORE, and no significant association (respectively, p=0.28, p=0.54) in models with PgR. Higher PgR was associated with better DDFS (p=0.001) in all multivariate assessments, including those with ER. Conclusions: DDFS was superior for patients with higher ER and PgR standardized units compared with those with HSCOREs &lt;-1. Adjunctive statistical standardization, similar to that mandated for clinical practice by the World Health Organization for BMD, should improve inter-laboratory comparability of biomarker results for similar patient populations. Biomarker N DDFS DDFS 5-year (%) 95% CI ER total 2900 ER &lt;-1 506 86 (82, 91) ER (-1, 0] 934 94 (92, 96) ER ( 0, 1] 919 94 (92, 96) ER &gt;1 541 96 (93, 98) PgR total 2726 PgR &lt;-1 734 89 (86, 92) PgR (-1, 0] 439 92 (89, 95) PgR ( 0, 1] 967 95 (93, 96) PgR &gt;1.0 586 98 (97,100) Citation Format: Judy-Anne Chapman, Jane Bayani, Sandip SenGupta, John MS Bartlett, Tammy Piper, Mary Anne Quintayo, Shakeel Virk, Paul Goss, James Ingle, Matthew Ellis, George Sledge Jr, George Budd, Manuela Rabaglio, Rafat Ansari, Richard Tozer, David D'Souza, Haji Chalchal, Silvana Spadafora, Vered Stearns, Edith A. Perez, Karen Gelmon, Timothy Whelan, Catherine Elliott, Lois Shepherd, Bingshu Chen, Karen Taylor. Adjunctive statistical standardization of quantitated machine image analysis of Estrogen and Progesterone Receptors: CCTG MA.27 trial [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-27-10.
Innovative, Interactive Platform for Personalized Asthmatic Care
Asala, E.D. Abou, Kethireddy, S., Dalton, David , Meersman, Mark, Alcantara, I., Gordon, Shepherd, Meta, E., Zein, Joe , Wu, C.-P. , Dalton, D., Gordon, S.

Mayo Clinic

C105. RESPIRATORY REVELATIONS: EPIDEMIOLOGIC STUDIES IN ASTHMA, COPD, AND LUNG FUNCTION | April 30, 2024 | Volume: No volume available | Issue: No issue available | Pages: A6760-A6760

10.1164/ajrccm-conference.2024.209.1_meetingabstracts.a6760 Get It

Abstract 305: Practice How You Play! An Innovative Two-Pronged Approach at Improving Resident and Allied Health Staff Performance During Code Blue Events
Fatunde, Olubadewa A. , Odneal, John, Schwind, Valarie, Egbe, Tiffany, Kirbow, Karin, Muddana, Prithvi, Neidlinger, Beth A, Stokes, Michelle, Wright, Belinda, Stokes, Michelle

Mayo Clinic

Circulation | December 19, 2023 | Volume: 148 | Issue: Suppl_1 | Pages: No page available

10.1161/circ.148.suppl_1.305 Get It

Introduction/Background: Cardiopulmonary arrest (Code Blue or CB) is a feared complication of severe medical illnesses. In-hospital CB events (CBE) have been estimated to have a mortality rate of only 30.4%. CBEsare difficult to prepare for and execute due many factors, including their low frequency, high complexity, and unpredictability. Research Questions/Hypothesis: Over 6 months (March - September 2019), we tested the effects of both adaptation of a Code Blue (CB) Team Leader (TL) checklist—aimed at improving resident leadership and communication—as well as implementation of an interdisciplinary in-hospital CB simulation to improve the performance of both resident physicians. Methods/Approach: Primary outcomes included change in resident confidence leading a CBE (i.e. Level of comfort as TL , confidence of diagnosis and management, confidence in code-related procedural skills), and familiarity with the institutional rapid response protocol. Secondary outcomes included self-reported confidence of nurses to execute their role, and both physician and nurse time to response. Confidence parameters were measured by a 10 point Likert scale. Pre-intervention, baseline cross-sectional survey values of the primary outcome were obtained from 24 internal medicine residents (12 PGY2s, 12 PGY3) over 6 months. Post-intervention, the cross-sectional survey was repeated. Results/Data (descriptive and inferential statistics): Statistics for residents displayed in table and figure 1. The level of nurse confidence increased from 7.5 to 8.25 over 5 months. The time to first response by residents has decreased by more than 50%. Conclusion(s) Our project improved the quality and resident level of comfort running Code Blue events among both residents and nurses.
The Effect of Exogenous Adenosine Triphosphate on Blood Flow Kinetics During Dynamic Forearm Exercise
Shepherd, John R. A. , Joyner, Michael J. , Dillon, Gabrielle A. , Dinenno, Frank A. , Curry, Timothy B. , Ranadive, Sushant M.

Mayo Clinic

The FASEB Journal | November 26, 2023 | Volume: 31 | Issue: S1 | Pages: No page available

10.1096/fasebj.31.1_supplement.840.9 Get It

Introduction Adenosine triphosphate (ATP) is a vasodilating metabolite that plays a role in exercise hyperemia. In humans, exogenous infusion of ATP elevates skeletal muscle blood flow values to that observed during moderate‐intensity exercise. Recently ATP has been shown to evoke prolonged vasodilation over 150 minutes without tachyphylaxis. However, the steady‐state hyperemic responses to superimposed forearm exercise remain unaltered. The kinetics of blood flow during the initiation of exercise remains not well understood. Therefore we evaluated the effects of prolonged exogenous infusion of ATP on exercise hyperemia during the transition between rest and initiation of exercise. Methods While supine, eight healthy young participants (4M/4F; 25±1 years) performed 5 minutes of rhythmic dynamic handgrip exercise bouts (20% of maximum), first during saline (control), then at minute 5 and minute 150 during a continuous ATP infusion into the brachial artery. Each duty cycle consisted of 1 second contraction and 2 second relaxation. Mean blood velocity (MBV; cm/s), forearm vascular conductance (FVC; ml/minutes/100 mmHg), and shear rate (8*MBV/diameter; seconds −1 ) were calculated. The kinetics at the onset of exercise was assessed by calculating the slope of the FVC responses for the first 20 duty cycles after the start of contractions. Data are presented as means ± SEM. Results During saline control FVC was 3.9±0.3 at rest and with exercise rose to 22.7±0.84 and 27.8±1.2 ml/minute/100mmHg at 30 seconds and 1 minute, respectively (P<0.05 for both). Infusion of ATP increased FVC (3.9±0.3 vs 43.1±2.0 ml/minutes/100 mmHg, P<0.05) at five minutes and to 61.0±1.1 ml/minutes/100 mmHg at 150 minutes (P<0.05) with no systemic hemodynamic changes. Prolonged infusion of ATP did not alter the kinetics at the onset of contractions over 20 duty cycles of exercise hyperemic responses compared to control (0.71±0.1 control vs 1.01±0.1 ml/minutes/100mmHg/cycle at 5 minutes and vs 0.65±0.1 at 150 minutes, P>0.05 for all). Shear rate significantly increased compared to control (92±5 vs 751±57 seconds −1 , P<0.05) but was not different across exercise responses during ATP infusion (751±57 at 5 minutes vs 549±46 seconds −1 at 150 minutes, P>0.05). Conclusions Our findings demonstrate that despite the ability of ATP to elevate blood flow to that observed during exercise, the blood flow kinetics for the initiation of dynamic exercise hyperemic response are unaffected and remain unaltered after 150 minutes of prolonged ATP infusion. Further investigation in needed to understand the role of ATP in regulating the blood flow kinetics during dynamic exercise in humans. Support or Funding Information This research was supported by National Institutes of Health Research Grants HL‐119337 and by CTSA UL1 TR000135. The Caywood Professorship via the Mayo Foundation also supported this study.
Effect of Nitric Oxide Synthase Inhibition on Plasma ATP during Hypoxia and Exercise Induced Vasodilation in Humans
Shepherd, John‐Roger A, Wolhart, Sarah C., Ranadive, Sushant M. , Dillon, Gabrielle A. , Shepherd, John‐Roger Mohan, Dinenno, Frank A. , Curry, Timothy B. , Joyner, Michael J.

Mayo Clinic

The FASEB Journal | November 26, 2023 | Volume: 31 | Issue: S1 | Pages: No page available

10.1096/fasebj.31.1_supplement.840.11 Get It

Introduction Adenosine triphosphate (ATP) is postulated to be a major player in the local control of skeletal muscle vascular tone during exercise. Exercise during hypoxic conditions significantly augments skeletal muscle blood flow and elevates venous plasma levels of ATP compared to normoxic conditions in young healthy adults. This suggests that the elevated levels of ATP during hypoxic exercise contribute to the augmented vasodilation. Nitric oxide synthase (NOS) inhibition has also been shown to blunt the effects of hypoxia on exercise vasodilation. Therefore, the aim of the current study was to evaluate the effect of NOS inhibition and hypoxia on vasodilator responses and plasma ATP levels during exercise in healthy young adults. Methods 10 young volunteers (age = 28 ± 1 years, 6 men/4 women) performed four minutes of forearm handgrip exercise at 20% of their maximal voluntary contraction (MVC). The forearm handgrip exercise was performed under normoxia and hypoxia (SpO2 = ~80%) with and without NOS inhibitor, LNMMA administered via a brachial artery catheter. Beat to beat blood pressure and heart rate were recorded. Forearm blood flow was measured using Doppler ultrasound and normalized for arterial pressure to determine forearm vascular conductance (FVC). Venous blood was obtained from a retrograde intravenous catheter at rest and during the last minute of each exercise bout. Plasma ATP was measured using the luciferin‐luciferase technique. Results During saline and normoxia FVC was 43.4 ± 8.4 at rest and 307.8 ± 22.6 ml/min/100mmHg during exercise. With hypoxia FVC increased to 59.35 ± 10.5 at rest and 370.9 ± 33.3 ml/min/100mmHg during exercise (both p<0.05 vs. normoxia). During LNMMA and normoxia FVC did not change significantly compared to saline 33.9 ± 4.4 at rest and 283.5 ± 23.2 ml/min/100mmHg during exercise. With hypoxia and LNMMA FVC was 35.04 ± 4.1 at rest (p>0.05 vs. normoxia) and 326.0 ± 23.9 ml/min/100mmHg during exercise (p<0.05 vs. normoxia). When changes from baseline are evaluated, hypoxia augmented the vasodilator responses exercise to exercise during both saline and LNMMA. ATP was higher during 20% MVC exercise with saline during hypoxia as compared to normoxia (65.6 ± 12.1 vs. 108.1 ± 23.2 versus nmol/L, p=0.058). It was also higher during 20% MVC exercise with LNMMA (81.7 ± 9.5 vs. 106.1 ± 14.7 nmol/L, p=0.055). When changes from baseline are evaluated, hypoxia augmented venous ATP concentration with exercise during both saline and LNMMA. Conclusions Our results suggest that increased endogenous ATP release during hypoxic exercise continued to evoke vasodilation during NOS inhibition. A likely source of this ATP is from red blood cells and this interpretation is consistent with findings demonstrating that NOS inhibition has limited effects on ATP mediated dilation in the human forearm. Support or Funding Information This research was supported by National Institutes of Health Research Grants HL‐119337, CTSA UL1 TR000135 and the Caywood Professorship via the Mayo Foundation