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537 citation(s) found for "Walker, J C".

Breast and Prostate Cancer Risks for MaleBRCA1andBRCA2Pathogenic Variant Carriers Using Polygenic Risk Scores
Barnes, Daniel R. , Silvestri, Valentina , Leslie, Goska , McGuffog, Lesley, Yang, Xin , Adlard, Julian , Agnarsson, Bjarni A. , Ahmed, Munaza, Aittomäki, Kristiina, Andrulis, Irene L. , Arason, Aðalgeir , Azzollini, Jacopo , Barkardóttir, Rósa B. , Barrowdale, Daniel , Belotti, Muriel, Berthet, Pascaline, Boonen, Susanne E. , Borg, Åke , Brady, Angela F., Brewer, Carole, Brunet, Joan , Bucalo, Agostino, Caldés, Trinidad , Cassingham, Hayley , Christensen, Lise Lotte , Cini, Giulia , Claes, Kathleen , Collaborators, GEMO Study, Collaborators, EMBRACE, Cortesi, Laura , Damante, Giuseppe , Darder, Esther , Davidson, Rosemarie, Leeneer, Kim De , Putter, Robin De , Valle, Jesús Del , Ding, Yuan Chun , Donaldson, Alan , Eason, Jacqueline , Eeles, Rosalind A. , Engel, Christoph , Evans, D. Gareth , Feliubadaló, Lídia , Frone, Megan N. , Frost, Debra, Gehrig, Andrea, Giraud, Sophie , Glendon, Gord , Goldgar, David E. , Greene, Mark H. , Gregory, Helen , Groß, Eva, Hahnen, Eric, Hamann, Ute, Hansen, Thomas van Overeem , Hanson, Helen , Horváth, Judit , Investigators, KConFab, Investigators, HEBON, Izatt, Louise , James, Paul A. , Janavičius, Ramūnas , Jensen, Uffe Birk , Johannsson, Oskar T., John, Esther M. , Kramer, Gero , Kroeldrup, Lone , Kruse, Torben A. , Lautrup, Charlotte Kvist , López‐Fernández, Adrià , Mai, Phuong L, Manoukian, Siranoush , Mátrai, Zoltán , Matricardi, Laura , Mebirouk, Noura, Meindl, Alfons , Montagna, Marco , Monteiro, Álvaro N.A. , Morrison, Patrick J. , Muranen, Taru , Nathanson, Katherine L. , Niederacher, Dieter , Oláh, Edith , Olopade, Olufunmilayo I. , Pedersen, Inge Søkilde , Peissel, Bernard , Peterlongo, Paolo , Petersen, Annabeth Høgh , Pinto, Pedro, Porteous, Mary, Pottinger, Caroline , Pujana, Miquel Angel, Ramser, Juliane, Rantala, Johanna, Rogers, Mark T., Rønlund, Karina, Abajo, A.M. SÁnchez De, Shah, Payal D. , Sharif, Saba , Side, Lucy, Stadler, Zsofia, Steele, Linda , Sutter, Christian , Tan, Yen Y. , Teixeira, Manuel R. , Teulé, Àlex , Thull, Darcy L. , Trainer, Alison H., Tripathi, Vishakha , Valentini, Virginia , Viel, Alessandra , Walker, Lisa, Wang‐Gohrke, Shan , Wappenschmidt, Barbara , Whaite, Anna , Offit, Kenneth, Thomassen, Mads , Schmutzler, Rita K., Simard, Jacques , Easton, Douglas F. , Chenevix‐Trench, Georgia , Antoniou, Antonis C. , Pujana, Miguel Ángel , Dennis, Joe , Yang, Xin , Adlard, Julian , Agnarsson, Bjarni A , Andrulis, Irene L , Arason, Adalgeir , Arnold, Norbert , Auber, Bernd , Azzollini, Jacopo , Barkardottir, Rosa B , Barrowdale, Daniel , Benitez, Javier , Boonen, Susanne E , Bozsik, Aniko , Brennan, Paul , Brunet, Joan , Bucalo, Agostino , Caligo, Maria A , Campbell, Ian G , Cassingham, Hayley , Cini, Giulia , Claes, Kathleen B M , Coppa, Anna , Cortesi, Laura , Darder, Esther , de la Hoya, Miguel , de Putter, Robin , Del Valle, Jesús , Domchek, Susan M , Donaldson, Alan , Eason, Jacqueline , Engel, Christoph , Fostira, Florentia , Frone, Megan , Glendon, Gord , Godwin, Andrew K. , Greene, Mark H , Hahnen, Eric , Hanson, Helen , Izatt, Louise , Izquierdo, Angel , James, Paul , John, Esther M , Kroeldrup, Lone , Kruse, Torben A , Lazaro, Conxi , Lesueur, Fabienne , Matrai, Zoltan , Montagna, Marco , Monteiro, Alvaro N , Morrison, Patrick J , Muranen, Taru A , Nathanson, Katherine L , Neuhausen, Susan L. , Nevanlinna, H , Nguyen-Dumont, Tu , Niederacher, Dieter , Palli, Domenico , Parsons, Michael T , Perez-Segura, Pedro , Peterlongo, Paolo , Pinto, Pedro , Pottinger, Caroline , Radice, Paolo , Robson, Mark , Rump, Andreas , Sharif, Saba , Steele, Linda , Stoppa-Lyonnet, Dominique , Teixeira, Manuel R , Thull, Darcy L , Tischkowitz, Marc D. , Toland, Amanda Ewart , Tommasi, Stefania , Toss, Angela , Tripathi, Vishakha , Valentini, Virginia , van Asperen, Christi J , Venturelli, Marta , Viel, Alessandra , Joseph, Vijai , Whaite, Anna , Simard, Jacques , Easton, Doug , Chenevix-Trench, Georgia , Ottini, Laura , Barnes, Daniel R , Leslie, Goska , Pujana, Miquel Angel , Eeles, Rosalind A , Evans, D Gareth , Matricardi, Laura , Olopade, Olufunmilayo I , Silvestri, Valentina , De Leeneer, Kim , Feliubadaló, Lidia , Hansen, Thomas van Overeem , Manoukian, Siranoush , Arnold, Norbert , Auber, Bernd , Balmañà, Judith , Barwell, Julian , Benı́tez, Javier , Bozsik, Anikó , Brady, Angela F., Buys, Saundra S. , Caligo, Maria A. , Campbell, Ian , Collaborators, GEMO Study, Collaborators, EMBRACE, Cook, Jackie A , Hoya, Miguel de la , Dı́ez, Orland , Domchek, Susan M. , Gallagher, David James , Hentschel, Julia , Investigators, KConFab, Investigators, HEBON, Izquierdo, Á. , Lázaro, Conxi , Lesueur, Fabienne , Mai, Phuong L, Maxwell, Kara N. , Meindl, Alfons , Nevanlinna, Heli , Nguyen‐Dumont, Tú , Palli, Domenico , Parsons, Michael T. , Radice, Paolo , Robson, Mark E. , Rump, Andreas , Singer, Christian F. , Stoppa‐Lyonnet, Dominique , Asperen, Christi J. van , Vijai, Joseph , Zanna, Ines , Couch, Fergus J. , Ottini, Laura

JNCI: Journal of the National Cancer Institute | July 26, 2021 | Volume: 114 | Issue: 1 | Pages: 109-122

10.1093/jnci/djab147 | PMID 34320204 Get It

AbstractBackgroundRecent population-based female breast cancer and prostate cancer polygenic risk scores (PRS) have been developed. We assessed the associations of these PRS with breast and prostate cancer risks for male BRCA1 and BRCA2 pathogenic variant carriers.Methods483 BRCA1 and 1318 BRCA2 European ancestry male carriers were available from the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA). A 147-single nucleotide polymorphism (SNP) prostate cancer PRS (PRSPC) and a 313-SNP breast cancer PRS were evaluated. There were 3 versions of the breast cancer PRS, optimized to predict overall (PRSBC), estrogen receptor (ER)–negative (PRSER-), or ER-positive (PRSER+) breast cancer risk.ResultsPRSER+ yielded the strongest association with breast cancer risk. The odds ratios (ORs) per PRSER+ standard deviation estimates were 1.40 (95% confidence interval [CI] =1.07 to 1.83) for BRCA1 and 1.33 (95% CI = 1.16 to 1.52) for BRCA2 carriers. PRSPC was associated with prostate cancer risk for BRCA1 (OR = 1.73, 95% CI = 1.28 to 2.33) and BRCA2 (OR = 1.60, 95% CI = 1.34 to 1.91) carriers. The estimated breast cancer odds ratios were larger after adjusting for female relative breast cancer family history. By age 85 years, for BRCA2 carriers, the breast cancer risk varied from 7.7% to 18.4% and prostate cancer risk from 34.1% to 87.6% between the 5th and 95th percentiles of the PRS distributions.ConclusionsPopulation-based prostate and female breast cancer PRS are associated with a wide range of absolute breast and prostate cancer risks for male BRCA1 and BRCA2 carriers. These findings warrant further investigation aimed at providing personalized cancer risks for male carriers and informing clinical management.
Phase 3 randomized trial of chemotherapy with or without oblimersen in older AML patients: CALGB 10201 (Alliance)
Walker, Alison R. , Marcucci, Guido , Yin, Jun , Blum, William , Kohlschmidt, Jessica, Mrózek, Krzysztof , Carroll, Andrew J. , Eisfeld, Ann-Kathrin, Kolitz, Jonathan E. , Thakuri, Mohan C., Sutamtewagul, Grerk , Vij, Ravi , Byrd, John C. , Bloomfield, Clara D. , Stone, Richard M. , Byrd, John C. , Jacobson, Sawyer , Sutamtewagul, Grerk , Larson, Richard A , Stock, Wendy , Eisfeld, Ann‐Kathrin , Wang, Eunice S. , Stuart, Robert K. , Larson, Richard A. , Byrd, John C

Blood Advances | July 12, 2021 | Volume: 5 | Issue: 13 | Pages: 2775-2787

10.1182/bloodadvances.2021004233 | PMID 34251414 Get It

Abstract Overexpression of B-cell leukemia/lymphoma 2 (BCL2) renders acute myeloid leukemia (AML) cells resistant to chemotherapy and has been associated with unfavorable outcomes. Oblimersen (G3139) is a phosphorothioate 18-mer antisense oligonucleotide directed against the first 6 BCL2 codons. In a phase 1 study of AML patients treated with G3139, cytarabine, and daunorubicin induction with cytarabine consolidation, no antisense-related toxicity was reported, and BCL2 downregulation occurred in patients achieving complete remission. In this phase 3 trial, untreated older AML patients were randomized to cytarabine (100 mg/m2 per day on days 4-10) and daunorubicin (60 mg/m2 per day on days 4-6) followed by cytarabine consolidation (2000 mg/m2 per day on days 4-8) with (arm A) or without (arm B) G3139 (7 mg/m2 per day on days 1-10 [induction] or days 1-8 [consolidation]). A total of 506 patients were enrolled. No differences in toxicity were observed between arms. Estimated overall survival (OS) at 1 year was 43% for arm A and 40% for arm B (1-sided log rank P = .13), with no differences in disease-free (DFS; P = .26) or event-free survival (P = .80). Subgroup analyses showed patients age <70 years in arm A had improved OS by 1 month vs those in arm B (P = .04), and patients with secondary AML in arm A had better DFS vs those in arm B (P = .04). We conclude that addition of G3139 to chemotherapy failed to improve outcomes of older AML patients. However, more effective means of inhibiting BCL2 are showing promising results in combination with chemotherapy in AML. This trial was registered at www.clinicaltrials.gov as #NCT00085124.
Ulnar Artery Access: A Nontraditional Access Site for Diagnostic Cerebral Angiography and Neurointervention: 2-Dimensional Operative Video
Dossani, Rimal H., Cappuzzo, Justin M. , Sonig, Ashish , Almayman, Faisal, Siddiqui, Adnan H. , Davies, Jason M. , Bain, Mark, Bendock, Bernard, Binning, Mandy J., Boulos, Alan S. , Crowley, Webster, Fessler, Richard D., Guterman, Lee R., Hoit, Daniel , Hopkins, L. Nelson , Howington, Jay U., James, Robert F. , Jankowitz, Brian T. , Kan, Peter , Khalessi, Alex A, Kim, Louis J. , Langer, David J. , Mack, William J. , Mericle, Robert A., Ogilvy, Chris, Replogle, Robert, Riina, Howard A. , Saugaveau, Eric, Schirmer, Clemens M. , Spiotta, Alex, Sultan, Ali, Turner, Raymond D , Veznedaroglu, Erol, Welch, Babu G. , White, Jonathan A. , Davies, Jason M , Siddiqui, Adnan H , Schirmer, Clemens M , Waqas, Muhammad , Levy, Elad I. , Arthur, Adam Stephen , Grande, Andrew Walker , Hanel, Ricardó A. , Kim, Louis J. , Lanzino, Giuseppe , Levitt, Michael R. , Lopes, Demetrius K. , Mocco, J , Pandey, Aditya S , Ringer, Andrew J. , Rodriguez, Rafael, Tawk, Rabih G. , Thomas, Ajith J

Operative Neurosurgery | June 30, 2021 | Volume: 21 | Issue: 4 | Pages: E350-E352

10.1093/ons/opab221 | PMID 34195817 Get It

Abstract Transfemoral access has long been the main access site for cerebral angiography and neurointerventional procedures. Radial access is accepted as an alternative to the traditional transfemoral approach. Ulnar access may be undertaken if the radial artery is occluded or small caliber, or when radial artery preservation is needed. The safety and feasibility of ulnar access for neuroangiographic procedures has been demonstrated. 1-3 In this operative video, we demonstrate ulnar artery access in a patient in whom radial artery preservation was desired. We further elaborate on the technical nuances of this access. This nontraditional access site offers the same advantages as radial access, avoiding the need to switch to femoral artery access. A preoperative Allen's test is not necessary. Ultrasound imaging is used to aid in the identification and successful puncture of the ulnar artery. A medial to lateral approach for ulnar artery puncture is advised to avoid injury to the ulnar nerve. Careful application of wrist closure bands avoids hematoma accumulation. The patient gave informed consent for the procedure and video recording. Institutional review board approval was deemed unnecessary. Video. © University at Buffalo, May 2021. Used with permission.
Rare Copy Number Variants (CNVs) and Breast Cancer Risk
Dorling, Leila , Bola, Manjeet, Wang, Qin , Andrulis, Irene L. , Antonenkova, Natalia, Aronson, Kristan J. , Freeman, Laura Beane, Beckmann, Matthias W. , Bojeson, Stig, Chang‐Claude, Jenny , Chenevix‐Trench, Georgia , Collaborators, NBCS, Collée, J. Margriet, Evans, D. Gareth , Fasching, Peter A. , Flyger, Henrik, Hahen, Eric, Haiman, Christopher A. , Hoppe, Reine, Investigators, ACTB, Investigators, kConFab, Jager, Agnes , Johnson, Nichola , Keeman, Renske , Ko, Yon‐Dschun, Kosma, Veli‐Matti , Kristensen, Vessela N. , Kubelka‐Sabit, Katerina , Kurian, Alison, Larson, Nicole L. , Linet, Martha S. , Łukomska, Alicja, Mannermaa, Arto , Mavroudis, Dimitrios, Park‐Simon, Tjoung‐Won , Peterlongo, Paolo , Plaseska-Karanfilska, Dijana, Sawyer, Elinor J. , Schmutzler, Rita K., Shibli, Rana , Soucy, Penny, Tomlinson, Ian , Vachon, Celine M. , Wendt, Camilla, Yang, Xiaohong R. , Easton, Douglas F. , Peterlongo, Paolo , Evans, D Gareth , Chenevix-Trench, Georgia , Sawyer, Elinor J , Dennis, Joe , Tyrer, Jonathan P. , Walker, Logan C. , Michailidou, Kyriaki , Ahearn, Thomas U. , Anton‐Culver, Hoda , Arndt, Volker , Behrens, Sabine , Benı́tez, Javier , Bermisheva, Marina , Bojesen, Stig E. , Brenner, Hermann , Castelao, Jose E. , Clarke, Christine L. , Couch, Fergus J. , Cox, Angela , Cross, Simon S. , Czene, Kamila , Devilee, Peter , Dörk, Thilo , Dossus, Laure , Eliassen, A. Heather , Eriksson, Mikael , Figueroa, Jonine D. , Fletcher, Olivia , Fritschi, Lin , Gabrielson, Marike , Gago-Domínguez, Manuela , García‐Closas, Montserrat , Giles, Graham G. , González‐Neira, Anna , Guénel, Pascal , Hall, Per N , Hollestelle, Antoinette , Hoppe, Reiner , Hopper, John L. , Howell, Anthony , Jakubowska, Anna , John, Esther M. , Jones, Michael E. , Jung, Audrey , Kaaks, Rudolf , Хуснутдинова, Э. К. , Kitahara, Cari M. , Koutros, Stella , Kraft, Peter , Lambrechts, Diether , Manoukian, Siranoush , Margolin, Sara , Milne, Roger L. , Muranen, Taru , Murphy, Rachel A. , Nevanlinna, Heli , Olson, Janet E. , Olsson, Håkan , Perou, Charles M. , Pylkäs, Katri , Rennert, Gad , Saloustros, Emmanouil , Sandler, Dale P. , Schmidt, Marjanka K. , Smeets, Ann , Southey, Melissa C. , Swerdlow, Anthony J. , Tamimi, Rulla M. , Taylor, Jack A. , Teras, Lauren R. , Terry, Mary Beth , Troester, Melissa A. , Truong, Thérèse , Vachon, Celine M. , Wendt, Camilla, Winqvist, Robert , Wolk, Alicja , Zheng, Wei , Ziogas, Argyrios , Simard, Jacques , Dunning, Alison M. , Pharoah, Paul D.P.

No container title available | June 22, 2021 | Volume: No volume available | Issue: No issue available | Pages: No page available

10.21203/rs.3.rs-602209/v1 Get It

Abstract BackgroundCopy number variants (CNVs) are pervasive in the human genome but potential disease associations with rare CNVs have not been comprehensively assessed in large datasets. We analysed rare CNVs in genes and non-coding regions for 86,788 breast cancer cases and 76,122 controls of European ancestry with genome-wide array data.ResultsGene burden tests detected the strongest association for deletions in BRCA1 (P= 3.7E-18). Nine other genes were associated with a p-value < 0.01 including known susceptibility genes CHEK2 (P= 0.0008), ATM (P= 0.002) and BRCA2 (P= 0.008). Outside the known genes we detected associations with p-values < 0.001 for either overall or subtype-specific breast cancer at nine deletion regions and four duplication regions. Three of the deletion regions were in established common susceptibility loci.ConclusionsThis is the first genome-wide analysis of rare CNVs in a large breast cancer case-control dataset. We detected associations with exonic deletions in established breast cancer susceptibility genes. We also detected suggestive associations with non-coding CNVs in known and novel loci with large effects sizes. Larger sample sizes will be required to reach robust levels of statistical significance.
Abstract WP479: Associations Between Vascular Risk, Amyloid Burden and Incident Dementia: The ARIC-PET Study
Wu, Aozhou , Sharrett, A. Richey , Wagenknecht, Lynne E. , Wong, Dean F. , Gottesman, Rebecca F. , Coresh, Josef , Jack, Clifford R. , Knopman, David S. , Rahmim, Arman , Walker, Keenan A. , Mosley, Thomas H.

Stroke | June 21, 2021 | Volume: 51 | Issue: Suppl_1 | Pages: No page available

10.1161/str.51.suppl_1.wp479 Get It

Background: Midlife vascular risk factors (MVRF) are associated with incident dementia. Similarly, amyloid β(Aβ) and neurodegeneration (e.g.brain volumes), as parts of the Alzheimer’s Disease (AD) ATN framework, are associated with cognition. Whether vascular and AD-associated factors contribute to dementia independently or interact synergistically to reduce cognitive ability is not well understood. Methods: Recruited from 3 U.S. communities, ARIC-PET participants were followed from 1987-89 (45-64 yo) through 2016-17 (74-94 yo). Cognition was evaluated in 2011-13 (ages 69-88), and twice more, every 2-3 years. In 2011-13, nondemented ARIC-PET participants had a brain MRI, with measurement of white matter hyperintensities (WMH) and brain volumes, with florbetapir (Aβ) PET scans in 2012-14; global cortical standardized uptake value ratio (SUVR) was log-transformed and standardized. Dementia was classified by expert review, as well as phone and medical record surveillance. The relative contributions of vascular risk (MVRF, WMH volume) and AD pathology (elevated Aβ SUVR, smaller AD signature region volumes) to incident dementia were evaluated with Cox proportional hazards regression. Results: In 298 individuals, 36 developed dementia. In models with key MVRF, demographics, and Aβ SUVR, hypertension and Aβ each independently predicted dementia risk (per SD of Aβ SUVR: HR 2.57, 95% CI 1.72-3.84; hypertension: HR 2.57, 95% CI 1.16-5.67), but didn’t interact on dementia risk. WMH (per SD: HR 1.51, 95% CI 1.03-2.20) and Aβ SUVR (per SD: HR 2.52, 95% CI 1.83-3.47) each contributed to incident dementia but WMH lost significance when MVRF were added to the model. Smaller AD signature regions were associated with incident dementia, independent of Aβ SUVR, and remained significant after adjustment for MVRF (HR per SD 2.18, 95% CI 1.18-4.01). Conclusions: Midlife hypertension and late-life Aβ independently contribute to dementia risk, but don’t synergize on a multiplicative scale. Neurodegeneration (e.g.smaller AD signature region volume) is also associated with incident dementia, independent of Aβ and MVRF. Multiple pathways leading to dementia should be considered when evaluating risk factors and interventions to reduce the burden of dementia.
Nitric oxide synthase (NOS) inhibition blunts the kinetics of vasodilation during dynamic forearm exercise
Walker, Branton G., Mohamed, Essa A. , Joyner, Michael J. , Casey, Darren P.

The FASEB Journal | June 21, 2021 | Volume: 26 | Issue: S1 | Pages: No page available

10.1096/fasebj.26.1_supplement.1138.45 Get It

We tested the hypothesis that local inhibition of NOS would 1) alter the kinetics of vasodilation during dynamic forearm (FA) exercise and 2) prolong the time to reach steady state (SS). Subjects (n=22) performed rhythmic FA exercise (20% of maximum) during saline infusion (control) and NOS inhibition (L‐NMMA). Additionally, a subset of subjects performed a third trial of FA exercise during combined inhibition of either 1) NOS and adenosine (aminophylline; n=9), or 2) NOS and prostaglandins (Ketorolac; n=8). Forearm vascular conductance (FVC; ml/min/100mmHg) was calculated from blood flow (ml/min) and blood pressure (mmHg). Vasodilator kinetics were assessed by calculating the slope of the FVC response for every duty cycle between baseline and SS exercise as well as the number of duty cycles (1s contraction/2s relaxation) to reach SS. NOS inhibition reduced the kinetics of vasodilation during dynamic FA exercise (8.5 ± 0.6 vs. 11.1 ± 0.8 FVC/duty cycle; P < 0.001 vs. control) and increased the time to reach SS (25.1 ± 1 vs. 32 ± 1 duty cycles; P < 0.001 vs. control). The kinetics of vasodilation were reduced further with combined inhibition of NOS and adenosine (6.2 ± 0.8 vs. 7.5 ± 0.6 FVC/duty cycle; P < 0.05 vs. L‐NMMA alone), but not with combined inhibition of NOS and prostaglandins. Our data indicate that NOS inhibition blunts the kinetics of vasodilation during dynamic FA exercise and prolongs the time to reach SS.
α‐adrenergic vasoconstriction contributes to the blunted skeletal muscle contraction‐induced rapid vasodilation with aging
Walker, Branton G., Roberts, Shelly K., Casey, Darren P. , Mohamed, Essa A. , Joyner, Michael J.

The FASEB Journal | June 21, 2021 | Volume: 26 | Issue: S1 | Pages: No page available

10.1096/fasebj.26.1_supplement.1138.9 Get It

We tested the hypothesis that elevated sympathetic tone is responsible for lower peak vasoldilation following single muscle contractions in older adults. Younger (n=8; 5M/3F, age 27 ± 2) and older (n=10; 5M/5F, age 69 ± 2) adults performed single forearm contractions at 10, 20 and 40% of maximum during 1) control, 2) sympathetic activation via lower body negative pressure (LBNP; ‐ 20mmHg), and 3) intra‐arterial infusion of phentolamine (α‐adrenergic antagonist). Brachial artery diameter and velocities were measured via Doppler ultrasound and forearm vascular conductance (FVC) was calculated from blood flow (ml/min) and blood pressure (mmHg). Peak vasodilator responses (ΔFVC from baseline) were attenuated in older adults for all intensities ( P < 0.05). LBNP reduced the ΔFVC at 10% (95 ± 18 vs. 60 ± 11), 20% (128 ± 9 vs. 91 ± 18) and 40% (192 ± 21 vs. 133 ± 23; P < 0.01 vs. control) in younger subjects, but not older adults (61 ± 6 vs. 58 ± 10; 99 ± 10 vs. 101 ± 17; 141 ± 17 vs. 129 ± 19, respectively; P = 0.53–0.97). With phentolamine ΔFVC was enhanced in older adults at each contraction intensity (91 ± 12, 136 ± 22, and 181 ± 22, respectively; P < 0.01 vs. control), but not younger adults (87 ± 9, 145 ± 12, and 192 ± 24, respectively; P = 0.31–1.0 vs. control). Our data indicate that overlying α‐adrenergic vasoconstriction plays a significant role in the age‐related decreases in skeletal muscle contraction‐induced rapid vasodilation.
Contribution of nitric oxide in the contraction‐induced rapid vasodilation in young and older adults
Walker, Branton G., Taylor, Jennifer L. , Casey, Darren P. , Ranadive, Sushant M. , Joyner, Michael J.

The FASEB Journal | June 21, 2021 | Volume: 27 | Issue: S1 | Pages: No page available

10.1096/fasebj.27.1_supplement.1136.7 Get It

We tested the hypothesis that reduced nitric oxide (NO) bioavailability contributes to the attenuated peak and total vasodilation following single muscle contractions in older adults. Young (n=8; 25 ± 2 yr) and older (n=9; 67 ± 2 yr) adults performed single forearm contractions at 10, 20 and 40% of maximum during saline infusion (control) and NO synthase (NOS) inhibition via L‐NMMA. Brachial artery diameter and velocities were measured using Doppler ultrasound and forearm vascular conductance (FVC) was calculated from blood flow (ml/min) and blood pressure (mmHg). Peak and total vasodilator responses (ΔFVC from baseline) were attenuated in older adults at all intensities (P < 0.05). NOS inhibition reduced the peak ΔFVC at 10% (95 ± 13 vs. 59 ± 10), 20% (134 ± 11 vs. 90 ± 12) and 40% (222 ± 30 vs. 143 ± 24) in young subjects (P < 0.05 for all) and in older adults at 10% (61 ± 5 vs. 48 ± 7, P < 0.05) and 20% (90 ± 8 vs. 70 ± 8, P < 0.05), but not 40% (129 ± 13 vs. 105 ± 11, P = 0.12). The relative (%) reduction in peak ΔFVC due to NOS inhibition was greater in young vs. older adults at 20% (−36 ± 5 vs. −22 ± 5%, P < 0.05) and 40% (−35 ± 7 vs. −17 ± 7%, P < 0.05). The reduction in the total vasodilator response (area under the curve) with NOS inhibition was also greater in young vs. older adults at 20 and 40%. Our data suggest that contraction‐induced rapid vasodilation is mediated in part by NO; however, it appears the NO contribution in the response is greater in young adults.
Effect of hyperoxia on contraction‐induced forearm blood flow dynamics in young healthy adults (1106.13)
Ranadive, Sushant, Walker, B.R., Taylor, Jennifer , Joyner, Michael J. , Walker, Branton, Casey, Darren P.

The FASEB Journal | June 16, 2021 | Volume: 28 | Issue: S1 | Pages: No page available

10.1096/fasebj.28.1_supplement.1106.13 Get It

Hyperoxia can cause substantial reductions in peripheral and coronary blood flow at rest and during exercise. We tested the hypothesis that hyperoxia may increase the time for forearm blood flow (FBF) to reach steady state (SS) levels during exercise. Young (n=11; 28±2yr) healthy adults performed rhythmic forearm contractions at 10% of their maximum voluntary contraction for 5 minutes. Each duty cycle consisted of 1 second contraction and 2 second relaxation. Brachial artery diameters and velocities were measured using Doppler Ultrasound and forearm blood flow (ml/min) was calculated from the mean velocity and diameter. The dynamics of FBF at the onset of exercise were assessed by calculating the slope of the FBF response for every duty cycle between baseline and steady state, and the number of duty cycles to reach steady state. The slope of the line plotted from baseline FBF to SS, had a significantly attenuated slope under hyperoxia (5.4±1.1 ml/min/cycle) as compared to normoxia (10.6±2.6 ml/min/cycle). In addition, the number of duty cycles performed under hyperoxia (33±4 cycles) was significantly higher as compared to normoxia (25±4 cycles) (P<0.02). Our data suggest that hyperoxia attenuates the contraction‐induced FBF from baseline to SS as compared to normoxia.
Aging is associated with slowed vasodilator kinetics in dynamically contracting muscle: role of nitric oxide (1106.10)
Walker, B.R., Casey, Darren P. , Walker, Branton, Ranadive, Sushant M. , Joyner, Michael J.

The FASEB Journal | June 16, 2021 | Volume: 28 | Issue: S1 | Pages: No page available

10.1096/fasebj.28.1_supplement.1106.10 Get It

We tested the hypothesis that aging would be associated with slowed vasodilator kinetics in contracting muscle in part due to a reduced nitric oxide (NO) bioavailability. Young (n=10; 24 ± 2 yr) and older (n=10; 67 ± 2 yr) adults performed rhythmic forearm exercise (4 min each) at 10, 20 and 30% of max during saline infusion (control) and NO synthase (NOS) inhibition. Brachial artery diameter and velocities were measured using Doppler ultrasound. Forearm vascular conductance (FVC) was calculated for each duty cycle (1s contraction/2s relaxation) from blood flow (ml/min) and blood pressure (mmHg) and fit with a monoexponential model. The main parameters derived from the model were the amplitude (Amp) of the FVC response and the number of duty cycles for FVC to change 63% of the steady‐state amplitude (τFVC). Under control conditions 1) the Amp of the response at 20 and 30% MVC was lower in older (240 ± 24 and 319 ± 33 ml/min/100mmHg) compared to young adults (338 ± 45 and 462 ± 52 ml/min/100mmHg; P < 0.05) and 2) τFVC was slower in older (10 ± 1, 13 ± 1 and 15 ± 1 duty cycles) compared to young (6 ± 1, 9 ± 1 and 11 ± 1 duty cycles) adults at all intensities ( P < 0.05). NOS inhibition blunted the Amp and slowed the τFVC in young, at all intensities (10 ± 2, 12 ± 1 and 16 ± 2 duty cycles; P < 0.05), whereas it did not change in older adults. Our data indicate that the vasodilator kinetics in exercising muscle are altered with aging likely due to blunted NO signaling. Grant Funding Source : Supported by NIH grants HL105467 (DPC), HL46493 (MJJ) and by CTSA UL1 TR000135