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Restaino RM, Cradock K, Barlow MA. Effects of the Follicular Menstrual Phase on Forearm Vascular Conductance in Abdominal Obese Premenopausal Women During Graded Handgrip Exercise. Artery Res 2022. [DOI: 10.1007/s44200-022-00017-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Abstract
Purpose
Previous studies have reported a sympatholytic action of estrogen on the vasculature in response to increased sympathetic outflow, an effect most notable during exercise, providing for necessary increases in blood flow to working muscle. In contrast, elevated concentrations of progesterone can inhibit this action of estrogen, impairing increases in blood flow. We hypothesize that the peak concentration of estrogen during the proliferative portion of the follicular phase of the menstrual cycle in female humans will increase vascular conductance during exercise when the effects of progesterone are negligible. In addition, we hypothesize that overweight abdominally obese females will have an attenuated conductance response to dynamic exercise during the same menstrual phase.
Methods
Participants engaged in graded forearm exercise using an isotonic handgrip dynometer with sequential increases in resistance at a cadence of 30 contractions/minute until task failure. They performed exercise at time points of the menstrual cycle corresponding to low concentrations of both sex hormones and elevated estrogen, while progesterone remained low. Blood flow and vascular conductance were measured using Doppler ultrasound.
Results
This revealed a trend that abdominal obese women during a phase of low estrogen had a lower overall blood flow and vascular conductance response than healthy controls at matching resistance stages during rest and exercise. This group difference was attenuated during the proliferative phase with elevated circulating estrogen. There is not a statistically significant interaction between Ovarian Phase and Weight group (P = 0.778).
Conclusion
The results indicate that overweight women are at a disadvantage during exercise in increasing blood flow to working muscles, which can be detrimental to overall fitness improvement during the early and potentially late follicular phase of the menstrual cycle.
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Somani YB, Moore DJ, Kim DJ, Gonzales JU, Barlow MA, Elavsky S, Proctor DN. Retrograde and oscillatory shear increase across the menopause transition. Physiol Rep 2019; 7:e13965. [PMID: 30604931 PMCID: PMC6317059 DOI: 10.14814/phy2.13965] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 11/26/2018] [Indexed: 12/29/2022] Open
Abstract
Declines in endothelial function can take place rapidly across the menopause transition, placing women at heightened risk for atherosclerosis. Disturbed patterns of conduit artery shear, characterized by greater oscillatory and retrograde shear, are associated with endothelial dysfunction but have yet to be described across menopause. Healthy women, who were not on hormone therapy or contraceptives, were classified into early perimenopausal, late perimenopausal, and early postmenopausal stage. Resting antegrade, retrograde, and oscillatory shear were calculated from blood velocity and diameter measured in the brachial and common femoral artery using Doppler ultrasound. Serum was collected for measurements of estradiol, follicle-stimulating hormone (FSH), and luteinizing hormone. After adjusting for age, brachial artery oscillatory shear was significantly higher in early postmenopausal women (n = 15, 0.17 ± 0.08 a.u.) than both early (n = 12, 0.08 ± 0.05 a.u., P < 0.05) and late (n = 8, 0.08 ± 0.04 a.u) perimenopausal women, and retrograde shear was significantly greater in early postmenopausal versus early perimenopausal women (-19.47 ± 12.97 vs. -9.62 ± 6.11 sec-1 , both P < 0.05). Femoral artery oscillatory and retrograde shear were greater, respectively, in early postmenopausal women (n = 15, 0.19 ± 0.08 a.u.; -13.57 ± 5.82 sec-1 ) than early perimenopausal women (n = 14, 0.11 ± 0.08 a.u.; -8.13 ± 4.43 sec-1 , P < 0.05). Further, Pearson correlation analyses revealed significant associations between FSH and both retrograde and oscillatory shear, respectively, in the brachial (r = -0.40, P = 0.03; r = 0.43, P = 0.02) and common femoral artery (r = -0.45, P = 0.01; r = 0.56, P = 0.001). These results suggest menopause, and its associated changes in reproductive hormones, adversely influences conduit arterial shear rate patterns to greater oscillatory and retrograde shear rates.
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Affiliation(s)
- Yasina B. Somani
- Department of KinesiologyPenn State UniversityUniversity ParkPennsylvania
| | | | | | | | | | | | - David N. Proctor
- Department of KinesiologyPenn State UniversityUniversity ParkPennsylvania
- Penn State College of MedicineHersheyPennsylvania
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Gomez AA, Szych KA, Rubio AA, Massey SA, Johnson AA, Gomez A, Jackson SA, Juarez LA, Weaver JM, Barlow MA. Insulin sensitivity and vascular responses to flow mediated dilation in Metabolic Syndrome women. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.713.13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | | | | | | | | | | | - John M. Weaver
- College of PharmacyUniversity of New Mexico Health Science CenterAlbuquerqueNM
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Szych K, Gomez A, Rubio A, Massey S, Johnson A, Gomez A, Jackson S, Juarez L, Weaver JM, Barlow MA. Measurement of nitric oxide bioavailability during dynamic handgrip exercise in women with Metabolic Syndrome. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.722.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Ariel Gomez
- BiologyEastern New Mexico UniversityPortalesNM
| | | | | | | | | | | | | | - John M. Weaver
- College of PharmacyUniversity of New Mexico Health Science CenterAlbuquerqueNM
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Moore DJ, Barlow MA, Gonzales JU, McGowan CL, Pawelczyk JA, Proctor DN. Evidence for the emergence of leg sympathetic vasoconstrictor tone with age in healthy women. Physiol Rep 2015; 3:3/1/e12275. [PMID: 25626874 PMCID: PMC4387747 DOI: 10.14814/phy2.12275] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
While muscle sympathetic nerve activity (MSNA) is elevated with advancing age, correlational evidence suggests that, in contrast to men, basal MSNA is not related to resting lower limb hemodynamics in women. However, limited data exists in women that have attempted to directly assess the degree of limb sympathetic vasoconstrictor tone, and whether it is altered with age. To address this issue, we measured changes in femoral artery vascular conductance (FVC) during an acute sympatho‐inhibitory stimulus (−60 mm Hg neck suction, NS) in groups of healthy younger (n = 8, 23 ± 1 years) and older (n = 7, 66 ± 1 years) women. The percent change in FVC in response to NS was significantly augmented in the older (P = 0.006 vs. young) women. Although NS caused no significant change (3 ± 3%, P = 0.33) in FVC in the young women, there was a robust increase in FVC (21 ± 5%, P = 0.003) in the old women. Collectively, these findings provide evidence that in women, leg sympathetic vasoconstrictor tone emerges with age. In the present study, we sought to compare the amount of sympathetic vasoconstriction in the resting lower limbs (i.e., legs) of younger and older women. Leg (femoral artery) vascular conductance increased in older but not younger women during an acute sympatho‐inhibitory stimulus. These findings suggest that in women there is an emergence of lower limb sympathetic vasoconstrictor tone with advanced age.
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Affiliation(s)
- David J Moore
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania Intercollege Graduate Degree Program in Physiology, The Pennsylvania State University, University Park, Pennsylvania
| | - Matthew A Barlow
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania Department of Biology, Eastern New Mexico University, Portales, New Mexico
| | - Joaquin U Gonzales
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania Department of Health, Exercise & Sport Sciences, Texas Tech University, Lubbock, Texas
| | - Cheri L McGowan
- Department of Kinesiology, University of Windsor, Windsor, Ontario, Canada
| | - James A Pawelczyk
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania Intercollege Graduate Degree Program in Physiology, The Pennsylvania State University, University Park, Pennsylvania
| | - David N Proctor
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania Intercollege Graduate Degree Program in Physiology, The Pennsylvania State University, University Park, Pennsylvania
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Restaino R, Schwermann T, Blankenship A, Barlow MA. Endogenous estrogen enhances brachial blood conductance during dynamic handgrip in young healthy and metabolic syndrome women. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.1136.9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Barlow MA, Gonzales JU, Proctor DN. Oral Tetrahydrobiopterin and the influence of age on female leg hemodynamics at rest and during exercise. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.1056.17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
This study tested the hypothesis that enkephalin increases femoral vascular conductance via the delta-2 phenotype of the opioid receptor (DOR-2) within peripheral sympathetic ganglia. Graded pulses of methionine–enkephalin (ME) were administered (0.03–10 μg/kg) into the terminal aorta of anesthetized dogs proximal to lumbar arteries that perfuse vasomotor ganglia regulating femoral blood flow. Femoral vascular conductance increased sharply (ED50 = 2.6 × 10−9 mol/kg) accompanied by declines in arterial pressure and femoral vascular resistance. A dose-related increase in arterial pressure preceded each subsequent fall in pressure. The DOR-2 antagonist, naltriben (NTB), abrogated the hyperemic effect of ME (ID50 = 1.4 × 10−9 mol/kg). DOR-1 blockade (BNTX) was five-fold less effective. The hyperemic effect of ME was also enhanced when sympathetic activity was reflexly increased by bilateral carotid occlusion. The DOR-2 agonist, deltorphin II, produced exaggerated increases in conductance compared with ME that were also reduced by DOR-2 blockade. DOR-1 blockade eliminated the initial pressor responses, exaggerated the subsequent depressor response, increased baseline femoral conductance 10-fold and shifted the ME-mediated hyperemic threshold one dose lower from 0.3 to 0.1 μg/kg, providing indirect support for a competing DOR-1-mediated constriction. Extended exposure to DOR-1 blockade lowered the maximal ME increase in conductance by 30%, suggesting that BNTX reduces the available pool of DOR receptors. In summary, enkephalin mediates a robust hyperemic effect through sympatholytic ganglionic DOR-2 receptors and DOR-1 antagonist studies provide indirect evidence for constituent opposition from a proposed DOR-1-mediated sympathotonic constrictor pathway.
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Affiliation(s)
- Matthew A Barlow
- Department of Integrative Physiology, Cardiovascular Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA
| | - Shekhar H Deo
- Department of Integrative Physiology, Cardiovascular Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA
| | - James L Caffrey
- Department of Integrative Physiology, Cardiovascular Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA
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Gonzales JU, Barlow MA, Onley N, Elavsky S, Proctor DN. Arterial Compliance And Responsiveness: Relative Impact Of Menopause And Fitness. Med Sci Sports Exerc 2010. [DOI: 10.1249/01.mss.0000384442.37108.d5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Mallet RT, Downey HF, Denning GM, Barlow MA, Caffrey JL. Intermittent hypoxia conditioning reduces DOR‐2 receptors in the canine SA node and improves vagal transmission. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.1022.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Robert T Mallet
- Integrative PhysiologyUniv North Texas Health Science CenterFort WorthTX
| | - H Fred Downey
- Integrative PhysiologyUniv North Texas Health Science CenterFort WorthTX
| | | | | | - James L Caffrey
- Integrative PhysiologyUniv North Texas Health Science CenterFort WorthTX
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Barlow MA, Deo SH, Gonzalez L, Yoshishige DA, Caffrey JL. Delta opioid receptors (DORs) and the Autonomic Control of the Heart and Circulation. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.789.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Shekhar H Deo
- Integrative Physiology ‐ CRI, UNTHSC‐Fort WorthFort WorthTX
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Deo SH, Barlow MA, Gonzalez L, Yoshishige D, Caffrey JL. Repeated arterial occlusion, delta-opioid receptor (DOR) plasticity and vagal transmission within the sinoatrial node of the anesthetized dog. Exp Biol Med (Maywood) 2008; 234:84-94. [PMID: 18997098 DOI: 10.3181/0808-rm-242] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Brief interruptions in coronary blood flow precondition the heart, engage delta-opioid receptor (DOR) mechanisms and reduce the damage that typically accompanies subsequent longer coronary occlusions. Repeated short occlusions of the sinoatrial (SA) node artery progressively raised nodal methionine-enkephalin-arginine-phenylalanine (MEAP) and improved vagal transmission during subsequent long occlusions in anesthetized dogs. The DOR type-1 (DOR-1) antagonist, BNTX reversed the vagotonic effect. Higher doses of enkephalin interrupted vagal transmission through a DOR-2 mechanism. The current study tested whether the preconditioning (PC) protocol, the later occlusion or a combination of both was required for the vagotonic effect. The study also tested whether evolving vagotonic effects included withdrawal of competing DOR-2 vagolytic influences. Vagal transmission progressively improved during successive SA nodal artery occlusions. The vagotonic effect was absent in sham animals and after DOR-1 blockade. After completing the PC protocol, exogenously applied vagolytic doses of MEAP reduced vagal transmission under both normal and occluded conditions. The magnitude of these DOR-2 vagolytic effects was small compared to controls and repeated MEAP challenges rapidly eroded vagolytic responses further. Prior DOR-1 blockade did not alter the PC mediated, progressive loss of DOR-2 vagolytic responses. In conclusion, DOR-1 vagotonic responses evolved from signals earlier in the PC protocol and erosion of competing DOR-2 vagolytic responses may have contributed to an unmasking of vagotonic responses. The data support the hypothesis that PC and DOR-2 stimulation promote DOR trafficking, and down regulation of the vagolytic DOR-2 phenotype in favor of the vagotonic DOR-1 phenotype. DOR-1 blockade may accelerate the process by sequestering newly emerging receptors.
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Affiliation(s)
- Shekhar H Deo
- University of North Texas Health Science Center, Department of Integrative Physiology, Cardiovascular Research Institute, Fort Worth, TX 76107, USA
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Deo SH, Barlow MA, Gonzalez L, Yoshishige D, Caffrey JL, Garcia T. Cholinergic location of delta opioid receptors in canine atria and sinoatrial node. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.1230.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Barlow MA, Sharma A, Gonzalez L, Garcia T, Smith ML, Yoshishige D, Caffrey JL. Valsalva ratios and insulin sensitivity. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.740.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Deo SH, Barlow MA, Gonzalez L, Yoshishige D, Caffrey JL. Cholinergic location of δ-opioid receptors in canine atria and SA node. Am J Physiol Heart Circ Physiol 2008; 294:H829-38. [DOI: 10.1152/ajpheart.01141.2007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
δ-Opioid receptors (DORs) are associated with ischemic preconditioning and vagal transmission in the sinoatrial (SA) node and atria. Although functional studies suggested that DORs are prejunctional on parasympathetic nerve terminals, their precise location remains unconfirmed. DORs were colocalized in tissue slices and synaptosomes from the canine right atrium and SA node along with cholinergic and adrenergic markers, vesicular acetylcholine transporter (VAChT), and tyrosine hydroxylase (TH). Synapsin I immunofluorescence verified the neural character of tissue structures and isolated synaptosomes. Acetylcholine and norepinephrine measurements suggested the presence of both cholinergic and adrenergic synaptosomes. Fluorescent analysis of VAChT and TH signals indicated that >80% of the synapsin-positive synaptosomes were of cholinergic origin and <8% were adrenergic. DORs colocalized 75–85% with synapsin in tissue slices from both atria and SA node. The colocalization was equally strong (85%) for nodal synaptosomes but less so for atrial synaptosomes (57%). Colocalization between DOR and VAChT was 75–85% regardless of the source. Overlap between DOR and TH was uniformly low, ranging from 8% to 17%. Western blots with synaptosomal extracts confirmed two DOR-positive bands at molecular masses corresponding to those reported for DOR monomers and dimers. The abundance of DOR was greater in nodal synaptosomes than in atrial synaptosomes, largely attributable to a greater abundance of monomers in the SA node. The abundant nodal and atrial DORs predominantly associated with cholinergic nerve terminals support the hypothesis that prejunctional DORs regulate vagal transmission locally within the heart.
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Sharma AB, Barlow MA, Yang SH, Simpkins JW, Mallet RT. Pyruvate enhances neurological recovery following cardiopulmonary arrest and resuscitation. Resuscitation 2007; 76:108-19. [PMID: 17618729 PMCID: PMC2737333 DOI: 10.1016/j.resuscitation.2007.04.028] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Revised: 04/11/2007] [Accepted: 04/19/2007] [Indexed: 01/07/2023]
Abstract
PURPOSE Cerebral oxidative stress and metabolic dysfunction impede neurological recovery from cardiac arrest-resuscitation. Pyruvate, a potent antioxidant and energy-yielding fuel, has been shown to protect against oxidant- and ischemia-induced neuronal damage. This study tested whether acute pyruvate treatment during cardiopulmonary resuscitation can prevent neurological dysfunction and cerebral injury following cardiac arrest. METHODS Anesthetized, open-chest mongrel dogs underwent 5 min cardiac arrest, 5 min open-chest cardiac compression (OCCC), defibrillation and 3-day recovery. Pyruvate (n=9) or NaCl volume control (n=8) were given (0.125 mmol kg(-1) min(-1) i.v.) throughout OCCC and the first 55 min recovery. Sham dogs (n=6) underwent surgery and recovery without cardiac arrest-resuscitation. RESULTS Neurological deficit score (NDS), evaluated at 2-day recovery, was sharply increased in NaCl-treated dogs (10.3+/-3.5) versus shams (1.2+/-0.4), but pyruvate treatment mitigated neurological deficit (NDS=3.3+/-1.2; P<0.05 versus NaCl). Brain samples were taken for histological examination and evaluation of inflammation and cell death at 3-day recovery. Loss of pyramidal neurons in the hippocampal CA1 subregion was greater in the NaCl controls than in pyruvate-treated dogs (11.7+/-2.3% versus 4.3+/-1.2%; P<0.05). Cardiac arrest increased caspase-3 activity, matrix metalloproteinase activity, and DNA fragmentation in the CA1 subregion; pyruvate prevented caspase-3 activation and DNA fragmentation, and suppressed matrix metalloproteinase activity. CONCLUSION Intravenous pyruvate therapy during cardiopulmonary resuscitation prevents initial oxidative stress and neuronal injury and enhances neurological recovery from cardiac arrest.
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Affiliation(s)
- Arti B. Sharma
- Department of Integrative Physiology, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - Matthew A. Barlow
- Department of Integrative Physiology, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - Shao-Hua Yang
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - James W. Simpkins
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - Robert T. Mallet
- Department of Integrative Physiology, University of North Texas Health Science Center, Fort Worth, Texas, USA
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Deo SH, Johnson-Davis S, Barlow MA, Yoshishige D, Caffrey JL. Repeated δ1-opioid receptor stimulation reduces δ2-opioid receptor responses in the SA node. Am J Physiol Heart Circ Physiol 2006; 291:H2246-54. [PMID: 16782849 DOI: 10.1152/ajpheart.00122.2006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ultra-low-dose methionine-enkephalin-arginine-phenylalanine improves vagal transmission (vagotonic) and decreases heart rate via δ1-opioid receptors within the sinoatrial (SA) node. Higher doses activate δ2-opioid receptors, interrupt vagal transmission (vagolytic), and reduce the bradycardia. Preconditioning-like occlusion of the nodal artery produced a vagotonic response that was reversed by the δ1-antagonist 7-benzylidenaltrexone (BNTX). The following study tested the hypothesis that extended δ1-opioid receptor stimulation reduces subsequent δ2-receptor responses. The δ2-agonist deltorphin II was introduced in the SA node by microdialysis to evaluate δ2 responses before and after infusion of the δ1-agonist TAN-67. TAN-67 reduced the vagolytic effect of deltorphin by two-thirds. When the δ1-antagonist BNTX was combined with TAN-67, the deltorphin response was preserved, suggesting that attrition of the prior response was mediated by δ1 activity. When TAN-67 was omitted in time control studies, some loss of δ2 responses was apparent in the absence of the δ1 treatment. This loss was also eliminated by BNTX, suggesting that the attenuation of the response after deltorphin alone was also the result of δ1 activity. Additional studies tested TAN-67 alone in the absence of prior deltorphin. When time controls were conducted without the initial deltorphin treatment, a robust vagolytic response was observed. When TAN-67 preceded the delayed deltorphin, the vagolytic response was eroded, indicating an independent effect of TAN-67. BNTX infused afterward was unable to restore the δ2 response. These data support the conclusion that the loss of the δ2 response resulted from reduced δ2 activity mediated by continued δ1-receptor stimulation and not the arithmetic consequence of increased competition from that same δ1 receptor.
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MESH Headings
- Analgesics/pharmacology
- Analgesics, Opioid/pharmacology
- Animals
- Benzylidene Compounds/pharmacology
- Bradycardia/drug therapy
- Bradycardia/physiopathology
- Dogs
- Dose-Response Relationship, Drug
- Enkephalin, Methionine/analogs & derivatives
- Enkephalin, Methionine/pharmacology
- Female
- Male
- Microdialysis
- Naltrexone/analogs & derivatives
- Naltrexone/pharmacology
- Narcotic Antagonists/pharmacology
- Oligopeptides/pharmacology
- Quinolines/pharmacology
- Receptors, Opioid, delta/classification
- Receptors, Opioid, delta/drug effects
- Receptors, Opioid, delta/metabolism
- Sinoatrial Node/drug effects
- Sinoatrial Node/innervation
- Sinoatrial Node/physiology
- Stimulation, Chemical
- Vagus Nerve/drug effects
- Vagus Nerve/physiology
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Affiliation(s)
- S H Deo
- Dept. of Integrative Physiology, Univ. of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth TX 76107, USA.
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Abstract
This study examined the hypothesis that vagotonic and sympatholytic effects of cardiac enkephalins are independently mediated by different receptors. A dose-response was constructed by administering the delta-receptor opioid methionine-enkephalin-arginine-phenylalanine (MEAP) by microdialysis into the interstitium of the canine sinoatrial node during vagal and sympathetic stimulation. The right cardiac sympathetic nerves were stimulated as they exited the stellate ganglion at frequencies selected to increase heart rate approximately 35 bpm. The right cervical vagus was stimulated at frequencies selected to produce a two-step decline in heart rate of 25 and 50 bpm. A six-step dose-response was constructed by recording heart rates during nerve stimulation as the dose of MEAP was increased between 0.05 pmol/min and 1.5 nmol/min. Vagal transmission improved during MEAP at 0.5 pmol/min. However, sympathetically mediated tachycardia was unaltered with any dose of MEAP. In Study 2, a similar dose-response was constructed with the kappa-opioid receptor agonist trans(+/-)-3-4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)cyclohexyl]benzeneacetamide-HCl (U-50488H) to illustrate an independent sympatholytic effect and to verify its kappa-receptor character. U-50488H gradually suppressed the sympathetic tachycardia, with a significant effect obtained only at the highest dose (1.5 nmol/min). U-50488H had no effect on vagally mediated bradycardia. Surprisingly, the sympatholytic effect was not reversed by withdrawing U-50488H or by the subsequent addition of the kappa-antagonist 17,17'-(dichloropropylmethyl)-6,6',7,7'-6,6'-imino-7,7'-binorphinan-3,4',14,14'-tetroldi-hydrochloride (norBNI). Study 3 was conducted to determine whether the sympatholytic effect of U-50488H could be prevented by norBNI. NorBNI blocked the sympatholytic effect of the U50488H for 90 mins. When norBNI was discontinued afterward and U-50488H was continued alone, a sympatholytic effect emerged within 30 mins. Collectively these observations support the hypothesis that the vagotonic influence of MEAP is not dependent on a sympatholytic influence. Furthermore, the sympatholytic effect is mediated independently by kappa-receptors. The sympatholytic effect of sustained kappa-receptor stimulation appears to evolve gradually into a functional state not easily reversed.
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Affiliation(s)
- Matthew A Barlow
- Department of Integrative Physiology, University of North Texas Health Science Center at Forth Worth, Fort Worth, TX 76107, USA
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Deo S, Barlow MA, Yoshishige D, Caffrey JL. 4‐TYROSYL‐ENKEPHALINS ARE INACTIVE IN HEART COMPARED TO THEIR VAGOLYTIC 4‐PHENYLALANYL‐PARENTS, MET‐ AND LEU‐ENKEPHALIN. FASEB J 2006. [DOI: 10.1096/fasebj.20.5.a1201-c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Shekhar Deo
- Integrative Physiology, UNTHSC3500 Camp Bowie BlvdFort WorthTX76107
| | - M A Barlow
- Integrative Physiology, UNTHSC3500 Camp Bowie BlvdFort WorthTX76107
| | - D Yoshishige
- Integrative Physiology, UNTHSC3500 Camp Bowie BlvdFort WorthTX76107
| | - J L Caffrey
- Integrative Physiology, UNTHSC3500 Camp Bowie BlvdFort WorthTX76107
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20
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Abstract
INTRODUCTION The Insertable Loop Recorder (ILR) has emerged as an important new tool in the diagnostic armamentarium for patients with syncope. METHODS AND RESULTS A case report illustrates how the ILR unexpectedly led to the diagnosis of seizure as the explanation for a man's recurrent, but infrequent episodes of sudden loss of consciousness. CONCLUSIONS This case raises the possibility that the development of implantable recording devices which monitor physiologic parameters other than cardiac rhythm (eg. brain, nerve or muscle activity) may provide the long-term monitoring capability needed to improve the diagnostic yield for conditions, such as seizures, which occur infrequently.
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Affiliation(s)
- C S Simpson
- Arrhythmia Service, London Health Sciences Centre London, Ontario, Canada.
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21
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Brooks WM, Stidley CA, Petropoulos H, Jung RE, Weers DC, Friedman SD, Barlow MA, Sibbitt WL, Yeo RA. Metabolic and cognitive response to human traumatic brain injury: a quantitative proton magnetic resonance study. J Neurotrauma 2000; 17:629-40. [PMID: 10972240 DOI: 10.1089/089771500415382] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Proton magnetic resonance spectroscopy (1H-MRS) offers a unique insight into brain cellular metabolism following traumatic brain injury (TBI). The aim of the present study was to assess change in neurometabolite markers of brain injury during the recovery period following TBI. We studied 19 TBI patients at 1.5, 3, and 6 months postinjury and 28 controls. We used 1H-MRS to quantify N-acetylaspartate (NAA), creatine (Cre), choline (Cho), and myoinositol (mIns) in occipitoparietal gray matter (GM) and white matter (WM) remote from the primary injury focus. Neuropsychological testing quantified cognitive impairment and recovery. At 1.5 months, we found cognitive impairment (mean z score = -1.36 vs. 0.18,p < 0.01), lower NAA (GM: 12.42 mM vs. 13.03, p = 0.01; WM: 11.75 vs. 12.81, p < 0.01), and elevated Cho (GM: 1.51 vs. 1.25, p < 0.01; WM: 1.98 vs. 1.79, p < 0.01) in TBI patients compared with controls. GM NAA at 1.5 months predicted cognitive function at outcome (6 months postinjury; r = 0.63, p = 0.04). GM NAA continued to fall by 0.46 mM between 1.5 and 3 months (p = 0.02) indicating continuing neuronal loss, metabolic dysfunction, or both. Between 3 and 6 months, WM NAA increased by 0.55 mM (p = 0.06) suggesting metabolic recovery. Patients with poorer outcomes had elevated mean GM Cho at 3 months postinjury, suggesting active inflammation, as compared to patients with better outcomes (p = 0.002). 1H-MRS offers a noninvasive approach to assessing neuronal injury and inflammation following TBI, and may provide unique data for patient management and assessment of therapeutic efficacy.
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Affiliation(s)
- W M Brooks
- Clinical & Magnetic Resonance Research Center, Department of Neurosciences, University of New Mexico, Albuquerque, USA.
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22
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Affiliation(s)
- M A Barlow
- University of Western Ontario, London, Canada
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23
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Barlow MA, Klein GJ, Simpson CS, Murgatroyd FD, Yee R, Krahn AD, Skanes AC. Unipolar electrogram characteristics predictive of successful radiofrequency catheter ablation of accessory pathways. J Cardiovasc Electrophysiol 2000; 11:146-54. [PMID: 10709708 DOI: 10.1111/j.1540-8167.2000.tb00313.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
INTRODUCTION The purpose of this study was to determine the characteristics of the unipolar electrogram that are most helpful in predicting successful radiofrequency ablation of accessory pathways. METHODS AND RESULTS The unipolar electrogram was analyzed at 185 ablation sites in 53 patients; 94 attempts were directed at the site of earliest atrial activation ("atrial group") and 91 at the site of earliest ventricular activation ("ventricular group"). The electrogram was analyzed for several features, including pattern ("QS" or "initial R"). Unipolar pattern: Overall, a "QS" pattern was seen at 55% of unsuccessful, 75% of temporarily successful, and 90% of permanently successful sites. For the atrial group, the respective frequencies were 53%, 77%, and 92%, and for the ventricular group, 57%, 73%, and 86%. The difference in pattern distribution between unsuccessful and permanently successful sites was significant for all groups: overall, P < 0.0001; atrial group, P = 0.0005; ventricular group, P = 0.02. Absence of a "QS" pattern (i.e., "initial R") predicted a 92% chance of unsuccessful ablation. Additional features: Activation times were significantly shorter at permanently successful than at unsuccessful (P < 0.0001) or temporarily successful sites (P = 0.0002). No significant differences were found in atrial or ventricular amplitudes or in A/V ratios. Intrinsic deflection slew was lower at temporarily successful sites (P = 0.03 vs all other sites). CONCLUSION Ablation at sites revealing an "initial R" pattern (i.e., absent "QS") is very unlikely to be successful. Activation time is shorter at successful sites. These features are equally applicable when mapping the atrial potential as when mapping the ventricular potential.
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Affiliation(s)
- M A Barlow
- Division of Cardiology, The University of Western Ontario, London, Canada
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24
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Maslow JN, Brecher S, Gunn J, Durbin A, Barlow MA, Arbeit RD. Variation and persistence of methicillin-resistant Staphylococcus aureus strains among individual patients over extended periods of time. Eur J Clin Microbiol Infect Dis 1995; 14:282-90. [PMID: 7649190 DOI: 10.1007/bf02116520] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
To determine the strain variation and persistence among isolates of methicillin-resistant Staphylococcus aureus (MRSA) cultured from patients with colonization over extended time spans, pulsed-field gel electrophoresis was used to analyze the isolates from 47 patients for whom at least two mecA-positive isolates collected a minimum of six months apart were available. For 22 (47%) patients, the isolates represented multiple distinct strains of Staphylococcus aureus, while 20 (43%) patients had only a single strain detected; five (11%) patients had similar, genetically related isolates. MRSA were frequently associated with mucocutaneous abnormalities; 29 (62%) patients had focal cutaneous defects, and ten (21%) had chronic dermatitis. Multiple strains of MRSA were detected more frequently than single strains among patients in whom the initial focus of MRSA resolved clinically and another mucocutaneous defect subsequently developed compared to patients with clinically persistent foci (11/15 versus 9/23, respectively; p = 0.05, Fisher's exact test). Among the 21 patients in this series for whom isolates cultured within a two-month time span were available, there were seven (33%) patients with multiple strains of MRSA, including one patient with polyclonal bacteremia. In summary, patients with long-term MRSA colonization often have several different strains of MRSA, which typically change overtime in association with removal or resolution of a colonized focus and the recurrence of mucocutaneous defects.
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Affiliation(s)
- J N Maslow
- Infectious Diseases Section, Boston University School of Medicine, Massachusetts, USA
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25
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Slutsky AM, Arbeit RD, Barber TW, Rich J, von Reyn CF, Pieciak W, Barlow MA, Maslow JN. Polyclonal infections due to Mycobacterium avium complex in patients with AIDS detected by pulsed-field gel electrophoresis of sequential clinical isolates. J Clin Microbiol 1994; 32:1773-8. [PMID: 7929773 PMCID: PMC263790 DOI: 10.1128/jcm.32.7.1773-1778.1994] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Invasive infection with organisms of the Mycobacterium avium complex (MAC) is common among patients with advanced human immunodeficiency virus infection. In previous studies, we analyzed multiple individual colonies of MAC isolated from specimens obtained at the same time and observed that 14 to 20% of patients are simultaneously infected with more than one strain. In this study, we examined sequential isolates from 12 patients with AIDS who had two or more MAC isolates available from clinical specimens collected more than 1 week apart; the intervals between the first and last specimens ranged from 8 to 192 (median, 46) days. For each isolate, restriction digests of genomic DNA were analyzed by pulsed-field gel electrophoresis; DNA was prepared by using a protocol, described here in detail, which had been optimized for conditions of bacterial growth and lysis. The pulsed-field gel electrophoresis analysis identified four patients (33%) infected with two different MAC strains. Both M. avium and M. intracellulare were cultured from blood specimens from two patients. In each of the four patients, the second strain was identified from a culture taken within 14 days of the initial study isolate, and in three of these patients, the first strain was detected again in a subsequent culture. These observations suggest that the presence of two different strains among isolates from sequential cultures may reflect ongoing polyclonal infection. We conclude that polyclonal infection with MAC is common among patients with AIDS. The identification of such infections may be critical in the development of effective treatments.
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Affiliation(s)
- A M Slutsky
- Infectious Diseases Section, VA Medical Center, Boston, Massachusetts 02130
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26
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Johnson VA, Barlow MA, Merrill DP, Chou TC, Hirsch MS. Three-drug synergistic inhibition of HIV-1 replication in vitro by zidovudine, recombinant soluble CD4, and recombinant interferon-alpha A. J Infect Dis 1990; 161:1059-67. [PMID: 2345291 DOI: 10.1093/infdis/161.6.1059] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Optimal management of human immunodeficiency virus type 1 (HIV-1) infections may require combinations of agents that attack different targets in the viral replicative cycle. Zidovudine (AZT), recombinant soluble CD4 (rsCD4), and recombinant interferon-alpha A (rIFN-alpha A) were evaluated in 2- and 3-drug regimens against HIV-1 replication in vitro. Peripheral blood mononuclear cells and a CD4+ T cell line (H9) were studied using multiple HIV-1 replicative end points. Drug interactions were evaluated by the median-effect principle and the isobologram technique. AZT, rsCD4, and rIFN-alpha A inhibited HIV-1 synergistically in 2- and 3-drug combinations. The 3-drug regimen provided more complete virus suppression than the 2-drug regimens. In H9 cells, single-drug regimens lost effectiveness at 10-14 days and 2-drug regimens lost effectiveness at 14-18 days. In contrast, the 3-drug regimen showed nearly complete suppression over 28 days in culture without toxicity. Clinical trials of these 3 drugs in combination should be considered.
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Affiliation(s)
- V A Johnson
- Infectious Disease Unit, Massachusetts General Hospital, Boston, MA 02114
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Johnson VA, Barlow MA, Chou TC, Fisher RA, Walker BD, Hirsch MS, Schooley RT. Synergistic inhibition of human immunodeficiency virus type 1 (HIV-1) replication in vitro by recombinant soluble CD4 and 3'-azido-3'-deoxythymidine. J Infect Dis 1989; 159:837-44. [PMID: 2785146 DOI: 10.1093/infdis/159.5.837] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
A combination of antiviral therapies that target different sites in the human immunodeficiency virus type 1 (HIV-1) replicative cycle may be necessary for optimal treatment of HIV-1 infections. We evaluated the interactions of a soluble virus receptor (recombinant soluble CD4 or rsT4) and a reverse transcriptase inhibitor (azidothymidine, AZT) against HIV-1 replication in vitro. A variety of cell types was studied including peripheral blood mononuclear cells, a CD4-positive T-cell line, and a CD4-positive human monocyte cell line. The combination of rsT4 and AZT inhibited HIV-1 synergistically over a broad range of drug concentrations and multiplicities of infection in several different HIV-1 replication assays. Drug interactions were evaluated by the median-effect principle and the isobologram technique using a computer analysis. In all of the cell types tested, combinations of rsT4 and AZT were synergistic in vitro, without additive cytotoxicity.
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Affiliation(s)
- V A Johnson
- Infectious Disease Unit, Massachusetts General Hospital, Boston 02114
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28
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Johnson VA, Walker BD, Barlow MA, Paradis TJ, Chou TC, Hirsch MS. Synergistic inhibition of human immunodeficiency virus type 1 and type 2 replication in vitro by castanospermine and 3'-azido-3'-deoxythymidine. Antimicrob Agents Chemother 1989; 33:53-7. [PMID: 2653214 PMCID: PMC171420 DOI: 10.1128/aac.33.1.53] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Castanospermine and 3'-azido-3'-deoxythymidine (zidovudine) were evaluated in combination against human immunodeficiency virus (HIV) replication in vitro. Castanospermine and 3'-azido-3'-deoxythymidine inhibited HIV type 1 synergistically in acutely infected H9 cells. In addition, they synergistically inhibited both HIV type 1 and HIV type 2 in peripheral blood mononuclear cells. There were no additional toxic effects of these agents in combination. Drug interactions were evaluated by the median-effect principle and the isobologram technique. Combinations of a glycosylation inhibitor, such as castanospermine, with 3'-azido-3'-deoxythymidine deserve consideration for HIV-related chemotherapeutic intervention.
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Affiliation(s)
- V A Johnson
- Infectious Disease Unit, Massachusetts General Hospital, Harvard Medical School, Boston 02114
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