Julian Stewart

Summary

Affiliation: New York Medical College
Country: USA

Publications

  1. ncbi request reprint Decreased microvascular nitric oxide-dependent vasodilation in postural tachycardia syndrome
    Marvin S Medow
    New York Medical College, Valhalla, NY, USA
    Circulation 112:2611-8. 2005
  2. doi request reprint Chronic fatigue syndrome: comments on deconditioning, blood volume and resulting cardiac function
    Julian M Stewart
    Department of Pediatrics and Physiology, New York Medical College, Hawthorne, NY 10532, USA
    Clin Sci (Lond) 118:121-3. 2010
  3. ncbi request reprint Plantar vibration improves leg fluid flow in perimenopausal women
    Julian M Stewart
    Depts of Pediatrics and Physiology, The Center for Pediatric Hypotension and Division of Pediatric Cardiology, Suite 618, Munger Pavilion, New York Medical College, Valhalla, NY 10595, USA
    Am J Physiol Regul Integr Comp Physiol 288:R623-9. 2005
  4. ncbi request reprint Relation of postural vasovagal syncope to splanchnic hypervolemia in adolescents
    Julian M Stewart
    Department of Pediatrics, The Center for Pediatric Hypotension, Suite 618, Munger Pavilion, New York Medical College, Valhalla, NY 10595, USA
    Circulation 110:2575-81. 2004
  5. ncbi request reprint Chronic orthostatic intolerance and the postural tachycardia syndrome (POTS)
    Julian M Stewart
    Department of Pediatrics and Physiology, New York Medical College Valhalla, New York, USA
    J Pediatr 145:725-30. 2004
  6. ncbi request reprint Splanchnic hyperemia and hypervolemia during Valsalva maneuver in postural tachycardia syndrome
    Julian M Stewart
    Department of Pediatrics, New York Medical College, Valhalla, NY, USA
    Am J Physiol Heart Circ Physiol 289:H1951-9. 2005
  7. ncbi request reprint Persistent splanchnic hyperemia during upright tilt in postural tachycardia syndrome
    Julian M Stewart
    Department of Pediatrics, New York Medical College, Valhalla, NY, USA
    Am J Physiol Heart Circ Physiol 290:H665-73. 2006
  8. ncbi request reprint Increased plasma angiotensin II in postural tachycardia syndrome (POTS) is related to reduced blood flow and blood volume
    Julian M Stewart
    Center for Pediatric Hypotension, New York Medical College, Valhalla, NY 10595, USA
    Clin Sci (Lond) 110:255-63. 2006
  9. ncbi request reprint Postural hypocapnic hyperventilation is associated with enhanced peripheral vasoconstriction in postural tachycardia syndrome with normal supine blood flow
    Julian M Stewart
    Department of Pediatrics, Research Division and Hypotension Laboratory, New York Medical College, Suite 3050, 19 Bradhurst Ave, Hawthorne, NY 10532, USA
    Am J Physiol Heart Circ Physiol 291:H904-13. 2006
  10. ncbi request reprint Changes in regional blood volume and blood flow during static handgrip
    Julian M Stewart
    Professor of Pediatrics and Physiology, Research Division and Hypotension Laboratory, New York Medical College, Suite 3050, 19 Bradhurst Ave, Hawthorne, NY 10532, USA
    Am J Physiol Heart Circ Physiol 292:H215-23. 2007

Research Grants

  1. Vascular Dysfunction in CFS
    Julian M Stewart; Fiscal Year: 2010
  2. Local Vasoconstriction in Postural Tachycardia Syndrome
    Julian Stewart; Fiscal Year: 2007
  3. Detecting Endothelial Dysfunction in Renal Failure
    Julian Stewart; Fiscal Year: 2007
  4. Circulatory Dysfunction in Chronic Fatigue Syndrome
    Julian Stewart; Fiscal Year: 2004
  5. Local Vasoconstriction in Postural Tachycardia Syndrome
    Julian M Stewart; Fiscal Year: 2010

Collaborators

Detail Information

Publications46

  1. ncbi request reprint Decreased microvascular nitric oxide-dependent vasodilation in postural tachycardia syndrome
    Marvin S Medow
    New York Medical College, Valhalla, NY, USA
    Circulation 112:2611-8. 2005
    ..One variant of postural tachycardia syndrome (POTS), designated low-flow POTS, is associated with decreased peripheral blood flow related to impaired local vascular regulation...
  2. doi request reprint Chronic fatigue syndrome: comments on deconditioning, blood volume and resulting cardiac function
    Julian M Stewart
    Department of Pediatrics and Physiology, New York Medical College, Hawthorne, NY 10532, USA
    Clin Sci (Lond) 118:121-3. 2010
    ..The circulatory consequences of reduced cardiac output may help to account for many of the findings of the syndrome...
  3. ncbi request reprint Plantar vibration improves leg fluid flow in perimenopausal women
    Julian M Stewart
    Depts of Pediatrics and Physiology, The Center for Pediatric Hypotension and Division of Pediatric Cardiology, Suite 618, Munger Pavilion, New York Medical College, Valhalla, NY 10595, USA
    Am J Physiol Regul Integr Comp Physiol 288:R623-9. 2005
    ....
  4. ncbi request reprint Relation of postural vasovagal syncope to splanchnic hypervolemia in adolescents
    Julian M Stewart
    Department of Pediatrics, The Center for Pediatric Hypotension, Suite 618, Munger Pavilion, New York Medical College, Valhalla, NY 10595, USA
    Circulation 110:2575-81. 2004
    ..The mechanisms of simple faint remain elusive. We propose that postural fainting is related to excessive thoracic hypovolemia and splanchnic hypervolemia during orthostasis compared with healthy subjects...
  5. ncbi request reprint Chronic orthostatic intolerance and the postural tachycardia syndrome (POTS)
    Julian M Stewart
    Department of Pediatrics and Physiology, New York Medical College Valhalla, New York, USA
    J Pediatr 145:725-30. 2004
  6. ncbi request reprint Splanchnic hyperemia and hypervolemia during Valsalva maneuver in postural tachycardia syndrome
    Julian M Stewart
    Department of Pediatrics, New York Medical College, Valhalla, NY, USA
    Am J Physiol Heart Circ Physiol 289:H1951-9. 2005
    ..Thus splanchnic hyperemia and hypervolemia are related to excessive phase II blood pressure reduction in POTS despite intense peripheral vasoconstriction. Factors other than autonomic dysfunction may play a role in POTS...
  7. ncbi request reprint Persistent splanchnic hyperemia during upright tilt in postural tachycardia syndrome
    Julian M Stewart
    Department of Pediatrics, New York Medical College, Valhalla, NY, USA
    Am J Physiol Heart Circ Physiol 290:H665-73. 2006
    ..Lower body vasoconstriction in high-flow POTS was abnormal, and vasoconstriction in low-flow POTS was sustained at initially elevated supine levels...
  8. ncbi request reprint Increased plasma angiotensin II in postural tachycardia syndrome (POTS) is related to reduced blood flow and blood volume
    Julian M Stewart
    Center for Pediatric Hypotension, New York Medical College, Valhalla, NY 10595, USA
    Clin Sci (Lond) 110:255-63. 2006
    ..The data suggest that plasma Ang II is increased in low-flow POTS patients with hypovolaemia, which may contribute to local blood flow dysregulation and reduced NO bioavailability...
  9. ncbi request reprint Postural hypocapnic hyperventilation is associated with enhanced peripheral vasoconstriction in postural tachycardia syndrome with normal supine blood flow
    Julian M Stewart
    Department of Pediatrics, Research Division and Hypotension Laboratory, New York Medical College, Suite 3050, 19 Bradhurst Ave, Hawthorne, NY 10532, USA
    Am J Physiol Heart Circ Physiol 291:H904-13. 2006
    ..Variability indexes suggested enhanced sympathetic activation in POTS(HC) compared with other subjects. The data suggest enhanced cardiac and peripheral sympathetic excitation in POTS(HC)...
  10. ncbi request reprint Changes in regional blood volume and blood flow during static handgrip
    Julian M Stewart
    Professor of Pediatrics and Physiology, Research Division and Hypotension Laboratory, New York Medical College, Suite 3050, 19 Bradhurst Ave, Hawthorne, NY 10532, USA
    Am J Physiol Heart Circ Physiol 292:H215-23. 2007
    ..We conclude that the exercise pressor reflex is associated with reduced baroreflex cardiovagal regulation and driven by increased cardiac output related to enhanced preload, cardiac contractility, and splanchnic blood mobilization...
  11. ncbi request reprint Noninvasive measure of microvascular nitric oxide function in humans using very low-frequency cutaneous laser Doppler flow spectra
    Julian M Stewart
    New York Medical College, Valhalla, New York, USA
    Microcirculation 14:169-80. 2007
    ..0095-0.021 Hz) do not. The authors investigated whether VLF LDF power is nitric oxide (NO) specific...
  12. ncbi request reprint Reduced central blood volume and cardiac output and increased vascular resistance during static handgrip exercise in postural tachycardia syndrome
    Julian M Stewart
    Department of Pediatrics, New York Medical College, Valhalla, New York, USA
    Am J Physiol Heart Circ Physiol 293:H1908-17. 2007
    ..While increased cardiac output and central blood volume characterizes controls, increased peripheral resistance with blunted or eliminated in central blood volume increments characterizes POTS and may contribute to exercise intolerance...
  13. ncbi request reprint Reduced body mass index is associated with increased angiotensin II in young women with postural tachycardia syndrome
    Julian M Stewart
    Center for Pediatric Hypotension, New York Medical College, Valhalla, NY 10595, USA
    Clin Sci (Lond) 113:449-57. 2007
    ..Patients with low-flow POTS had decreased body mass, but decreased body mass alone cannot account for findings of peripheral vasoconstriction. In conclusion, the findings suggest that reduced body mass relates to increased plasma AngII...
  14. ncbi request reprint Cutaneous neuronal nitric oxide is specifically decreased in postural tachycardia syndrome
    Julian M Stewart
    The Center for Pediatric Hypotension, New York Medical College, Ste 3050, 19 Bradhurst Ave, Hawthorne, NY 10532, USA
    Am J Physiol Heart Circ Physiol 293:H2161-7. 2007
    ..The data suggest that nNO activity but not NO of endothelial NOS origin is reduced in low-flow POTS...
  15. ncbi request reprint Angiotensin II type 1 receptor blockade corrects cutaneous nitric oxide deficit in postural tachycardia syndrome
    Julian M Stewart
    The Center for Pediatric Hypotension, New York Medical College, 19 Bradhurst Avenue, Hawthorne, NY 10532, USA
    Am J Physiol Heart Circ Physiol 294:H466-73. 2008
    ..53 +/- 2 %CVC(max)). The data suggest that the reduction in cutaneous NO-dependent vasodilation in low-flow POTS is corrected by AT(1)R blockade...
  16. pmc Defects in cutaneous angiotensin-converting enzyme 2 and angiotensin-(1-7) production in postural tachycardia syndrome
    Julian M Stewart
    The Center for Pediatric Hypotension, Suite 1600 S, 19 Bradhurst Ave, New York Medical College, Hawthorne, NY 10532, USA
    Hypertension 53:767-74. 2009
    ..Data imply impaired catabolism of Ang II through the ACE2 pathway. Vasoconstriction in POTS may result from a reduction in Ang-(1-7) and an increase in Ang II...
  17. ncbi request reprint Reciprocal splanchnic-thoracic blood volume changes during the Valsalva maneuver
    Julian M Stewart
    Department of Pediatrics, New York Medical College, Valhalla, New York 10595, USA
    Am J Physiol Heart Circ Physiol 288:H752-8. 2005
    ..Changes in baseline splanchnic vascular properties may account for variability in thoracic blood volume changes during the Valsalva maneuver...
  18. ncbi request reprint Noninvasive interrogation of microvasculature for signs of endothelial dysfunction in patients with chronic renal failure
    Julian Stewart
    Division of Nephrology and Renal Research Institute, New York Medical College, Center for Pediatric Hypotension, Suite 618, Munger Pavilion, Valhalla, NY 10595, USA
    Am J Physiol Heart Circ Physiol 287:H2687-96. 2004
    ....
  19. ncbi request reprint Orthostatic hypotension in pediatrics
    Julian M Stewart
    Department of Pediatrics and Physiology, The Center for Pediatric Hypotension, New York Medical College Children s Hospital at Westchester Medical Center, Valhalla, New York 10595, USA
    Heart Dis 4:33-9. 2002
    ..However, persistent orthostatic hypotension and chronic symptoms of orthostatic intolerance indicate postural tachycardia syndrome...
  20. ncbi request reprint Orthostasis fails to produce active limb venoconstriction in adolescents
    J M Stewart
    Department of Pediatrics, The Center for Pediatric Hypotension, New York Medical College, Valhalla, NY 10595, USA
    J Appl Physiol 91:1723-9. 2001
    ..The volume-pressure relation was unchanged by orthostatic maneuvers. The results suggest that active venoconstriction in the limbs is not important to mild orthostatic response...
  21. ncbi request reprint Inappropriate early hypotension in adolescents: a form of chronic orthostatic intolerance with defective dependent vasoconstriction
    J M Stewart
    Department of Pediatrics, The Center for Pediatric Hypotension, New York Medical College, Valhalla, NY 10595, USA
    Pediatr Res 50:97-103. 2001
    ..The data suggest that INOH occurs in patients with chronic orthostatic intolerance and orthostatic tachycardia and is related to rapid caudal blood flow when upright because of a vasoconstrictor defect...
  22. ncbi request reprint Vascular perturbations in the chronic orthostatic intolerance of the postural orthostatic tachycardia syndrome
    J M Stewart
    Department of Pediatrics, Center for Pediatric Hypotension, New York Medical College, Valhalla, New York 10595, USA
    J Appl Physiol 89:1505-12. 2000
    ..Such findings make the POTS patients particularly vulnerable for edema fluid collection. This may signify a redistribution of blood to the lower extremities even while supine, accounting for tachycardia through vagal withdrawal...
  23. ncbi request reprint Pooling in chronic orthostatic intolerance: arterial vasoconstrictive but not venous compliance defects
    Julian M Stewart
    Department of Pediatrics and Physiology, New York Medical College, Valhalla, NY 10595, USA
    Circulation 105:2274-81. 2002
    ..My colleagues and I tested the hypothesis that pooling results from increased venous compliance in POTS patients...
  24. ncbi request reprint Clinical and physiological effects of an acute alpha-1 adrenergic agonist and a beta-1 adrenergic antagonist in chronic orthostatic intolerance
    Julian M Stewart
    Department of Pediatrics, New York Medical College, Valhalla, NY 10595, USA
    Circulation 106:2946-54. 2002
    ..POTS may be associated with increased limb blood flow ("high flow") and defective orthostatic vasoconstriction or decreased limb blood flow ("low flow") and potentially with small blood volume...
  25. ncbi request reprint Intravenous cannulation of adolescents does not affect the modulation of autonomic tone assessed by heart rate and blood pressure variability
    J M Stewart
    Department of Pediatrics, New York Medical College, Valhalla 10595, USA
    Clin Auton Res 10:7-12. 2000
    ..v. insertion. There were no differences from the groups that did not receive i.v. insertions. Data suggest, at most, a limited effect of i.v. insertion on autonomic function in adolescents...
  26. ncbi request reprint Contrasting neurovascular findings in chronic orthostatic intolerance and neurocardiogenic syncope
    Julian M Stewart
    Department of Pediatrics, New York Medical College, Valhalla, NY 10595, U S A
    Clin Sci (Lond) 104:329-40. 2003
    ..We conclude that peripheral vascular physiology in patients with POTS is abnormal, in contrast with normal peripheral vascular physiology in neurocardiogenic syncope...
  27. ncbi request reprint Microvascular filtration is increased in postural tachycardia syndrome
    Julian M Stewart
    Department of Pediatrics and Physiology, New York Medical College, Valhalla, NY 10595, USA
    Circulation 107:2816-22. 2003
    ..Postural tachycardia syndrome (POTS) is related to defective peripheral vasoconstriction of dependent extremities with redistributive hypovolemia...
  28. ncbi request reprint Neurally mediated hypotension and autonomic dysfunction measured by heart rate variability during head-up tilt testing in children with chronic fatigue syndrome
    J Stewart
    Department of Pediatrics, New York Medical College, Valhalla 10595, USA
    Clin Auton Res 8:221-30. 1998
    ..Taken together these data may indicate autonomic impairment in patients with CFS...
  29. ncbi request reprint Regional blood volume and peripheral blood flow in postural tachycardia syndrome
    Julian M Stewart
    Department of Pediatrics, New York Medical College, Valhalla, New York 10595, USA
    Am J Physiol Heart Circ Physiol 287:H1319-27. 2004
    ..The data demonstrate enhanced thoracic hypovolemia during upright tilt and confirm that POTS is related to inadequate cardiac venous return during orthostasis...
  30. ncbi request reprint Local vascular responses affecting blood flow in postural tachycardia syndrome
    Julian M Stewart
    Department of Pediatrics, Center for Pediatric Hypotension and Division of Pediatric Cardiology, Suite 618, Munger Pavilion, New York Medical College, Valhalla, NY 10595, USA
    Am J Physiol Heart Circ Physiol 285:H2749-56. 2003
    ..29 +/- 4 and 28 +/- 4 s; cutaneous time constant = 60 +/- 25 vs. 149 +/- 53 s in controls). Local blood flow regulation in low-flow POTS is impaired...
  31. ncbi request reprint Effects of thoracic blood volume on Valsalva maneuver
    Julian M Stewart
    Department of Pediatrics, New York Medical College, Valhalla, NY 10595, USA
    Am J Physiol Heart Circ Physiol 287:H798-804. 2004
    ..The VM depends on vascular as well as autonomic activation, which broadens its utility but complicates its analysis...
  32. ncbi request reprint Decreased skeletal muscle pump activity in patients with postural tachycardia syndrome and low peripheral blood flow
    Julian M Stewart
    Center for Pediatric Hypotension and Division of Pediatric Cardiology, Suite 618, Munger Pavilion, New York Medical College, Valhalla, NY 10595, USA
    Am J Physiol Heart Circ Physiol 286:H1216-22. 2004
    ..Decreased calf blood flow may reduce calf size in POTS and thereby impair the upright ejective ability of the skeletal muscle pump and further contribute to overall reduced blood flow and orthostatic intolerance in these patients...
  33. pmc Peripheral vascular adaptation and orthostatic tolerance in Fontan physiology
    Usha S Krishnan
    Department of Pediatric Cardiology, New York Medical College, Valhalla, NY 10595, USA
    Circulation 120:1775-83. 2009
    ..We hypothesized that chronically increased systemic venous pressures lead to adaptive changes in regional and peripheral vessels to maintain cardiac output, especially when patients are upright...
  34. ncbi request reprint Tetrasomy 21 transient leukemia with a GATA1 mutation in a phenotypically normal trisomy 21 mosaic infant: case report and review of the literature
    Claudio Sandoval
    Department of Pediatrics, New York Medical College, Valhalla, New York 10595, USA
    Pediatr Blood Cancer 44:85-91. 2005
    ..Transient leukemia in trisomy 21 mosaicism recapitulates the condition observed in constitutional trisomy 21 at the biological and clinical levels. Infants should be followed for the development of acute leukemia...
  35. ncbi request reprint Pathophysiology, diagnosis, and treatment of orthostatic hypotension and vasovagal syncope
    Marvin S Medow
    Department of Pediatrics, New York Medical College, Valhalla, New York 10595, USA
    Cardiol Rev 16:4-20. 2008
    ..Treatment for recurrent vasovagal syncope includes increased salt and water intake and various drug treatments, most of which are still under investigation...
  36. pmc Increased vasoconstriction predisposes to hyperpnea and postural faint
    Indu Taneja
    Department of Pediatrics, New York Medical College, Hawthorne, NY 10532, USA
    Am J Physiol Heart Circ Physiol 295:H372-81. 2008
    ..Hyperpnea and pulmonary stretch may contribute to the sympathoinhibition that occurs at the time of faint...
  37. pmc Reduced iron stores and its effect on vasovagal syncope (simple faint)
    Julian M Stewart
    J Pediatr 153:9-11. 2008
  38. ncbi request reprint Orthostatic intolerance in pediatrics
    Julian M Stewart
    Department of Pediatrics and Physiology, The Center for Pediatric Hypotension, New York Medical College, Valhalla 10595, USA
    J Pediatr 140:404-11. 2002
  39. ncbi request reprint Effect of plantar micromechanical stimulation on cardiovascular responses to immobility
    Guruprasad Madhavan
    Clinical Sciences Research Center, Department of Bioengineering, Thomas J Watson School of Engineering and Applied Science, State University of New York, Binghamton, New York, USA
    Am J Phys Med Rehabil 84:338-45. 2005
    ..We investigated the cardiovascular responses of adult women to the influence of extended quiet sitting and the extent to which these responses may be reversed by micromechanical stimulation of the plantar surface...
  40. ncbi request reprint Cardiovascular systemic regulation by plantar surface stimulation
    Guruprasad Madhavan
    Department of Orthopaedics, School of Medicine, Health Sciences Center, State University of New York, Stony Brook, USA
    Biomed Instrum Technol 40:78-84. 2006
    ..Here, we investigate the potential of low-magnitude vibration, applied at the plantar surface, to inhibit the cardiovascular responses of adult women to the orthostatic stress associated with quiet sitting...
  41. ncbi request reprint Transient orthostatic hypotension is common in adolescents
    Julian M Stewart
    Department of Pediatric, The Center for Pediatric Hypotension, New York Medical College, Valhalla 10595, USA
    J Pediatr 140:418-24. 2002
    ..We hypothesized that transient hypotension associated with the symptom of lightheadedness with standing is a common phenomenon in healthy adolescents but may be mistaken for orthostatic intolerance...
  42. ncbi request reprint Differential effects of lower body negative pressure and upright tilt on splanchnic blood volume
    Indu Taneja
    Department of Pediatrics, New York Medical College, Hawthorne, NY 10532, USA
    Am J Physiol Heart Circ Physiol 292:H1420-6. 2007
    ..Splanchnic emptying in LBNP models regional vascular changes during hemorrhage. Splanchnic filling may limit the ability of the splanchnic bed to respond to thoracic hypovolemia during upright posture...
  43. pmc Intradermal angiotensin II administration attenuates the local cutaneous vasodilator heating response
    Julian M Stewart
    New York Medical College, Hawthorne, NY 10532, USA
    Am J Physiol Heart Circ Physiol 295:H327-34. 2008
    ..ANG II mediates the AT(1)R blunting of local heating, which is not exclusively NO dependent, and is improved by antioxidant supplementation...
  44. ncbi request reprint The postural tachycardia syndrome
    Marvin S Medow
    Department of Pediatrics, New York Medical College, Valhalla, New York 10598, USA
    Cardiol Rev 15:67-75. 2007
    ..Treatments have resulted in varying degrees of success and are often used in combination with each other...
  45. ncbi request reprint Cyclooxygenase and nitric oxide synthase dependence of cutaneous reactive hyperemia in humans
    Marvin S Medow
    Department of Pediatrics, The Center for Pediatric Hypotension, New York Medical College, 19 Bradhurst Avenue, Hawthorne, NY 10532, USA
    Am J Physiol Heart Circ Physiol 293:H425-32. 2007
    ..Low-dose NLA + SNP duplicates the Keto response. Isoproterenol increased baseline and peak reactive flow. These results suggest that COX inhibition unmasks NO dependence of reactive hyperemia in human cutaneous circulation...
  46. ncbi request reprint Midodrine for the treatment of vasovagal syncope (simple faint)
    Julian M Stewart
    J Pediatr 149:740-2. 2006

Research Grants15

  1. Vascular Dysfunction in CFS
    Julian M Stewart; Fiscal Year: 2010
    ..These may be due to defects in a fundamental signaling molecule called nitric oxide (NO). In the current application we will determine how NO produces POTS in CFS patients and whether drugs that alter NO can improve patient health. ..
  2. Local Vasoconstriction in Postural Tachycardia Syndrome
    Julian Stewart; Fiscal Year: 2007
    ..Verifying these hypotheses will improve our ability to diagnose and treat an important cause of vascular pathophysiology in man. ..
  3. Detecting Endothelial Dysfunction in Renal Failure
    Julian Stewart; Fiscal Year: 2007
    ..These data will form the basis of future noninvasive prognostic testing and treatment of patients at risk for ECD and can provide a means to follow treatment modalities. ..
  4. Circulatory Dysfunction in Chronic Fatigue Syndrome
    Julian Stewart; Fiscal Year: 2004
    ....
  5. Local Vasoconstriction in Postural Tachycardia Syndrome
    Julian M Stewart; Fiscal Year: 2010
    ..In the current proposal we will perform sophisticated tests of the circulation and nervous systems to study the causes and mechanisms in these patients and we will test drug treatments. ..