19 results on '"Crawford BH"'
Search Results
2. Bioactive nanoparticles improve calcium handling in failing cardiac myocytes.
- Author
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Maxwell JT, Somasuntharam I, Gray WD, Shen M, Singer JM, Wang B, Saafir T, Crawford BH, Jiang R, Murthy N, Davis ME, and Wagner MB
- Subjects
- Acetylglucosamine chemistry, Calcium metabolism, Calcium Signaling drug effects, Heart Failure metabolism, Humans, Myocytes, Cardiac drug effects, Myocytes, Cardiac pathology, Nanoparticles chemistry, S100 Proteins metabolism, Sarcomeres metabolism, Sarcomeres pathology, Acetylglucosamine administration & dosage, Heart Failure drug therapy, Myocytes, Cardiac metabolism, Nanoparticles administration & dosage
- Abstract
Aims: To evaluate the ability of N-acetylglucosamine (GlcNAc) decorated nanoparticles and their cargo to modulate calcium handling in failing cardiac myocytes (CMs)., Materials & Methods: Primary CMs isolated from normal and failing hearts were treated with GlcNAc nanoparticles in order to assess the ability of the nanoparticles and their cargo to correct dysfunctional calcium handling in failing myocytes., Results & Conclusion: GlcNAc particles reduced aberrant calcium release in failing CMs and restored sarcomere function. Additionally, encapsulation of a small calcium-modulating protein, S100A1, in GlcNAc nanoparticles also showed improved calcium regulation. Thus, the development of our bioactive nanoparticle allows for a 'two-hit' treatment, by which the cargo and also the nanoparticle itself can modulate intracellular protein activity., Competing Interests: Financial & competing interests disclosure This publication has been funded in whole or in part with the federal funds from the National Heart, Lung and Blood Institute, NIH, Department of Health and Human Services, under Contract No. HHSN268201000043C, as well as grant HL090601 to ME Davis and American Heart Association grant 11GRNT7490000 to MB Wagner. The authors also wish to acknowledge the support of the Children's Miracle Network gift to Children's Healthcare of Atlanta, funding from the Center for Pediatric Nanomedicine at Georgia Institute of Technology and Children's Healthcare of Atlanta. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. No writing assistance was utilized in the production of this manuscript.
- Published
- 2015
- Full Text
- View/download PDF
3. Dysregulation of catalase activity in newborn myocytes during hypoxia is mediated by c-Abl tyrosine kinase.
- Author
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Cabigas EB, Liu J, Boopathy AV, Che PL, Crawford BH, Baroi G, Bhutani S, Shen M, Wagner MB, and Davis ME
- Subjects
- Animals, Animals, Newborn, Cell Hypoxia physiology, Enzyme Activation physiology, Rabbits, Rats, Rats, Sprague-Dawley, Catalase metabolism, Genes, abl physiology, Myocytes, Cardiac enzymology, Protein-Tyrosine Kinases physiology
- Abstract
In the adult heart, catalase (CAT) activity increases appropriately with increasing levels of hydrogen peroxide, conferring cardioprotection. This mechanism is absent in the newborn for unknown reasons. In the present study, we examined how the posttranslational modification of CAT contributes to its activation during hypoxia/ischemia and the role of c-Abl tyrosine kinase in this process. Hypoxia studies were carried out using primary cardiomyocytes from adult (>8 weeks) and newborn rats. Following hypoxia, the ratio of phosphorylated to total CAT and c-Abl in isolated newborn rat myocytes did not increase and were significantly lower (1.3- and 4.2-fold, respectively; P < .05) than their adult counterparts. Similarly, there was a significant association (P < .0005) between c-Abl and CAT in adult cells following hypoxia (30.9 ± 8.2 to 70.7 ± 13.1 au) that was absent in newborn myocytes. Although ubiquitination of CAT was higher in newborns compared to adults following hypoxia, inhibition of this did not improve CAT activity. When a c-Abl activator (5-(1,3-diaryl-1H-pyrazol-4-yl)hydantoin [DPH], 200 µmol/L) was administered prior to hypoxia, not only CAT activity was significantly increased (P < .05) but also phosphorylation levels were also significantly improved (P < .01) in these newborn myocytes. Additionally, ischemia-reperfusion (IR) studies were performed using newborn (4-5 days) rabbit hearts perfused in a Langendorff method. The DPH given as an intracardiac injection into the right ventricle of newborn rabbit resulted in a significant improvement (P < .002) in the recovery of developed pressure after IR, a key indicator of cardiac function (from 74.6% ± 6.6% to 118.7% ± 10.9%). In addition, CAT activity was increased 3.92-fold (P < .02) in the same DPH-treated hearts. Addition of DPH to adult rabbits in contrast had no significant effect (from 71.3% ± 10.7% to 59.4% ± 12.1%). Therefore, in the newborn, decreased phosphorylation of CAT by c-Abl potentially mediates IR-induced dysfunction, and activation of c-Abl may be a strategy to prevent ischemic injury associated with surgical procedures., (© The Author(s) 2014.)
- Published
- 2015
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- View/download PDF
4. A proliferative burst during preadolescence establishes the final cardiomyocyte number.
- Author
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Naqvi N, Li M, Calvert JW, Tejada T, Lambert JP, Wu J, Kesteven SH, Holman SR, Matsuda T, Lovelock JD, Howard WW, Iismaa SE, Chan AY, Crawford BH, Wagner MB, Martin DI, Lefer DJ, Graham RM, and Husain A
- Subjects
- Animals, Cell Separation, Male, Mice, Mice, Inbred C57BL, Myocytes, Cardiac physiology, Triiodothyronine metabolism, Cell Differentiation, Cell Proliferation, Heart growth & development, Myocytes, Cardiac cytology
- Abstract
It is widely believed that perinatal cardiomyocyte terminal differentiation blocks cytokinesis, thereby causing binucleation and limiting regenerative repair after injury. This suggests that heart growth should occur entirely by cardiomyocyte hypertrophy during preadolescence when, in mice, cardiac mass increases many-fold over a few weeks. Here, we show that a thyroid hormone surge activates the IGF-1/IGF-1-R/Akt pathway on postnatal day 15 and initiates a brief but intense proliferative burst of predominantly binuclear cardiomyocytes. This proliferation increases cardiomyocyte numbers by ~40%, causing a major disparity between heart and cardiomyocyte growth. Also, the response to cardiac injury at postnatal day 15 is intermediate between that observed at postnatal days 2 and 21, further suggesting persistence of cardiomyocyte proliferative capacity beyond the perinatal period. If replicated in humans, this may allow novel regenerative therapies for heart diseases., (Copyright © 2014 Elsevier Inc. All rights reserved.)
- Published
- 2014
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5. Cardioprotection from oxidative stress in the newborn heart by activation of PPARγ is mediated by catalase.
- Author
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Chen T, Jin X, Crawford BH, Cheng H, Saafir TB, Wagner MB, Yuan Z, and Ding G
- Subjects
- Age Factors, Anilides pharmacology, Animals, Animals, Newborn, Catalase genetics, Catalase metabolism, Hydrogen Peroxide pharmacology, L-Lactate Dehydrogenase analysis, Organ Culture Techniques, PPAR gamma agonists, PPAR gamma antagonists & inhibitors, Pioglitazone, RNA, Messenger biosynthesis, Rabbits, Rosiglitazone, Up-Regulation, Ventricular Function, Left drug effects, Cardiotonic Agents pharmacology, Heart drug effects, Oxidative Stress, PPAR gamma metabolism, Thiazolidinediones pharmacology
- Abstract
Regulation of catalase (CAT) by peroxisome proliferator-activated receptor-γ (PPARγ) was investigated to determine if PPARγ activation provides cardioprotection from oxidative stress caused by hydrogen peroxide (H(2)O(2)) in an age-dependent manner. Left ventricular developed pressure (LVDP) was measured in Langendorff perfused newborn or adult rabbit hearts, exposed to 200μM H(2)O(2), with perfusion of rosiglitazone (RGZ) or pioglitazone (PGZ), PPARγ agonists. We found: (1) H(2)O(2) significantly decreased sarcomere shortening in newborn ventricular cells but not in adult cells. Lactate dehydrogenase (LDH) release occurred earlier in newborn than in adult heart, which may be due, in part, to the lower expression of CAT in newborn heart. (2) RGZ increased CAT mRNA and protein as well as activity in newborn but not in adult heart. GW9662 (PPARγ blocker) eliminated the increased CAT mRNA by RGZ. (3) In newborn heart, RGZ and PGZ treatment inhibited release of LDH in response to H(2)O(2) compared to H(2)O(2) alone. GW9662 decreased this inhibition. (4) LVDP was significantly higher in both RGZ+H(2)O(2) and PGZ+H(2)O(2) groups than in the H(2)O(2) group. Block of PPARγ abolished this effect. In contrast, there was no effect of RGZ in adult. (5) The cardioprotective effects of RGZ were abolished by inhibition of CAT. In conclusion, PPARγ activation is cardioprotective to H(2)O(2)-induced stress in the newborn heart by upregulation of catalase. These data suggest that PPARγ activation may be an effective therapy for the young cardiac patient., (Copyright © 2012 Elsevier Inc. All rights reserved.)
- Published
- 2012
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6. Stretch-activated channel activation promotes early afterdepolarizations in rat ventricular myocytes under oxidative stress.
- Author
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Wang Y, Joyner RW, Wagner MB, Cheng J, Lai D, and Crawford BH
- Subjects
- Animals, Arrhythmias, Cardiac metabolism, Arrhythmias, Cardiac physiopathology, Cardiac Pacing, Artificial, Cations, Female, Heart Ventricles metabolism, Hydrogen Peroxide toxicity, Ion Channels drug effects, Male, Membrane Potentials, Models, Cardiovascular, Myocytes, Cardiac drug effects, Oxidants toxicity, Patch-Clamp Techniques, Rats, Rats, Sprague-Dawley, Stress, Mechanical, Time Factors, Calcium Signaling drug effects, Cell Shape drug effects, Ion Channels metabolism, Mechanotransduction, Cellular drug effects, Myocardial Contraction drug effects, Myocytes, Cardiac metabolism, Oxidative Stress drug effects
- Abstract
Mechanical stretch and oxidative stress have been shown to prolong action potential duration (APD) and produce early afterdepolarizations (EADs). Here, we developed a simulation model to study the role of stretch-activated channel (SAC) currents in triggering EADs in ventricular myocytes under oxidative stress. We adapted our coupling clamp circuit so that a model ionic current representing the actual SAC current was injected into ventricular myocytes and added as a real-time current. This current was calculated as I(SAC) = G(SAC) * (V(m) - E(SAC)), where G(SAC) is the stretch-activated conductance, V(m) is the membrane potential, and E(SAC) is the reversal potential. In rat ventricular myocytes, application of G(SAC) did not produce sustained automaticity or EADs, although turn-on of G(SAC) did produce some transient automaticity at high levels of G(SAC). Exposure of myocytes to 100 microM H(2)O(2) induced significant APD prolongation and increase in intracellular Ca(2+) load and transient, but no EAD or sustained automaticity was generated in the absence of G(SAC). However, the combination of G(SAC) and H(2)O(2) consistently produced EADs at lower levels of G(SAC) (2.6 +/- 0.4 nS, n = 14, P < 0.05). Pacing myocytes at a faster rate further prolonged APD and promoted the development of EADs. SAC activation plays an important role in facilitating the development of EADs in ventricular myocytes under acute oxidative stress. This mechanism may contribute to the increased propensity to lethal ventricular arrhythmias seen in cardiomyopathies, where the myocardium stretch and oxidative stress generally coexist.
- Published
- 2009
- Full Text
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7. Dephosphorylation specificities of protein phosphatase for cardiac troponin I, troponin T, and sites within troponin T.
- Author
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Jideama NM, Crawford BH, Hussain AK, and Raynor RL
- Subjects
- Animals, Cyclic AMP-Dependent Protein Kinases metabolism, Kinetics, Male, Myofibrils metabolism, Phosphorylation, Protein Kinase C metabolism, Rats, Rats, Sprague-Dawley, Substrate Specificity, Troponin T chemistry, Myocardium metabolism, Protein Phosphatase 1 metabolism, Troponin I metabolism, Troponin T metabolism
- Abstract
Protein dephosphorylation by protein phosphatase 1 (PP1), acting in concert with protein kinase C (PKC) and protein kinase A (PKA), is a pivotal regulatory mechanism of protein phosphorylation. Isolated rat cardiac myofibrils phosphorylated by PKC/PKA and dephosphorylated by PP1 were used in determining dephosphorylation specificities, Ca(2+)-stimulated Mg(2+)ATPase activities, and Ca(2+) sensitivities. In reconstituted troponin (Tn) complex, PP1 displayed distinct substrate specificity in dephosphorylation of TnT preferentially to TnI, in vitro. In situ phosphorylation of cardiomyocytes with calyculin A, a protein phosphatase inhibitor, resulted in an increase in the phosphorylation stiochiometry of TnT (0.3 to 0.5 (67%)), TnI (2.6 to 3.6 (38%)), and MLC2 (0.4 to 1.7 (325%)). These results further confirmed that though MLC2 is the preferred target substrate for protein phosphatase in the thick filament, the Tn complex (TnI and TnT) from thin filament and C-protein in the thick filament are also protein phosphatase substrates. Our in vitro dephosphorylation experiments revealed that while PP1 differentially dephosphorylated within TnT at multiple sites, TnI was uniformly dephosphorylated. Phosphopeptide maps from the in vitro experiments show that TnT phosphopeptides at spots 4A and 4B are much more resistant to PP1 dephosphorylation than other TnT phosphopeptides. Mg(2+)ATPase assays of myofibrils phosphorylated by PKC/PKA and dephosphorylated by PP1 delineated that while PKC and PKA phosphorylation decreased the Ca(2+)-stimulated Mg(2+)ATPase activities, dephosphorylation antagonistically restored it. PKC and PKA phosphorylation decreased Ca(2+) sensitivity to 3.6 microM and 5.0 microM respectively. However, dephosphorylation restored the Mg(2+)ATPase activity of PKC (99%) and PKA (95%), along with the Ca(2+) sensitivities (3.3 microM and 3.0 microM, respectively).
- Published
- 2006
- Full Text
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8. [Instrument for color identification for the blind].
- Author
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Crawford BH
- Subjects
- Humans, Transistors, Electronic, Blindness, Color, Sensory Aids
- Published
- 1975
- Full Text
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9. The influence of energy intake and percentage of body fat on the reproductive performance of nonpregnant mares.
- Author
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Kubiak JR, Crawford BH, Squires EL, Wrigley RH, and Ward GM
- Abstract
Sixty mares in transition from winter anestrus to normal cyclicity were assigned to a 3 x 2 factorial experiment to determine the effect of energy intake and percentage of body fat on the interval to first ovulation. The factors were 1) percentage of body fat--thin (<11.5), good (11.5 to 15), or fat (>15); and 2) energy intake--maintenance (100% of National Research Council (NRC) digestible energy requirement for maintenance) or high energy (150% of NRC digestible energy requirement for maintenance). Percentage of body fat was estimated by ultrasonographic scanning of rump fat thickness. Energy treatments began on April 2 and ended on June 4. Mares were teased daily with a stallion and their ovaries were palpated per rectum daily or every third day. A high energy intake was effective in hastening ovulation for mares in the thin group (P < 0.05) but not for mares in the moderate or fat groups. Mares in the fat group had a shorter (P < 0.05) interval from April 2 to ovulation (26.4 +/- 4.2 d) than those in the good or high energy-thin groups (48.7 +/- 2.8 and 49.1 +/- 4.2 d, respectively). Duration of the initial estrus was shorter (P < 0.05) for mares in the fat group (16.2 +/- 5.7 d) compared with mares in the good group (34.7 +/- 3.9 d) and tended (P<0.12) to be shorter than mares in the high energy-thin group (29.0 +/- 5.7 d).
- Published
- 1987
- Full Text
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10. Fiber types and size in equine skeletal muscle.
- Author
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Aberle ED, Judge MD, Kirkham WW, Page EH, and Crawford BH
- Subjects
- Adenosine Triphosphatases metabolism, Animals, Histocytochemistry, Myosins, NADH Tetrazolium Reductase metabolism, Horses anatomy & histology
- Abstract
Frozen sections of equine musculus semitendinosus were examined for myosin adenosine triphosphatase (ATPase) and reduced nicotinamide adenine dinucleotide-tetrazolium reductase (NADH-TR), using standard histochemical procedures, and the proportions of the various fiber types and average fiber sectional size were determined. With ATPase staining, approximately 70% of the fibers were classified as alpha fibers (ATPase positive), and 30%, as beta fibers (ATPase negative). In addition, 2 populations of alpha fibers could be readily distinguished on the basis of the intensity of the ATPase reaction, and these were designated alpha positive and alpha intermediate. The relationship of this difference in ATPase reaction to contraction speed of the fibers is not known. With NADH-TR staining, fibers were classified as either red fibers (positive) having aerobic metabolism or white fibers (negative) having primarily anaerobic metabolism. All beta fibers were red by NADH-TR; thus, they conformed to the criteria for beta R fibers. All alpha positive fibers were white by NADH-TR, as were most of the alpha intermediate fibers, and would be classified alpha W. Some of the alpha intermediate fibers gave an intermediate reaction with NADH-TR and could be classified as alpha R fibers which have not transformed to alpha W fibers. The alpha positive fibers were 7 to 10 mum larger in diameter than either beta or alpha intermediate fibers.
- Published
- 1976
11. The scotopic visibility curve and cone intrusion.
- Author
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Crawford BH and Palmer DA
- Subjects
- Color, Dark Adaptation, Humans, Photometry, Sensory Thresholds physiology, Photoreceptor Cells physiology, Visual Perception physiology
- Abstract
The scotopic visibility curves of two observers have been measured by determining their absolute thresholds for monochromatic lights and by direct comparison matching just above the threshold, in a 10 degree field with its centre 15 degrees above the fixation point. The results were all similar to the CIE scotopic curve. However, the threshold results in the long-wave part of the spectrum could be considerably modified by subliminal red and green lights. This is consistent with Drum's observations of sub-additivity at threshold. Above threshold, supra-additivity was obtained. A scotopic curve is evidently a non-linear combination of rod and cone responses which varies with the conditions of observation.
- Published
- 1985
- Full Text
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12. An inexpensive photostimulator for searching the receptive fields of a single unit in the visualpathway.
- Author
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Crawford BH and Ikeda H
- Subjects
- Visual Perception, Optics and Photonics instrumentation, Photoreceptor Cells physiology
- Published
- 1970
13. Multiple fistulation of the equine large intestine.
- Author
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Baker JP, Sutton HH, Crawford BH Jr, and Lieb S
- Subjects
- Animals, Horses, Intestinal Fistula veterinary, Intestine, Large surgery
- Published
- 1969
- Full Text
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14. Steep frequency-of-seeing curves.
- Author
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CRAWFORD BH and PIRENNE MH
- Subjects
- Light, Vision, Ocular
- Published
- 1954
- Full Text
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15. Visual adaptation in relation to brief conditioning stimuli.
- Author
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CRAWFORD BH
- Subjects
- Conditioning, Classical, Conditioning, Psychological, Reflex, Vision, Ocular
- Published
- 1947
- Full Text
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16. Portal and carotid catheterization of the equine.
- Author
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Baker JP, Sutton HH, Lieb S, and Crawford BH Jr
- Subjects
- Animals, Intubation veterinary, Methods, Carotid Arteries, Catheterization veterinary, Horses, Portal Vein
- Published
- 1970
- Full Text
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17. Photochemical laws and visual phenomena.
- Author
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CRAWFORD BH
- Subjects
- Light chemistry, Vision, Low, Vision, Ocular chemistry
- Published
- 1946
- Full Text
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18. The fundamental processes of vision.
- Author
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CRAWFORD BH
- Subjects
- Humans, Vision, Ocular
- Published
- 1948
19. Colour matching and adaptation.
- Author
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Crawford BH
- Subjects
- Humans, Adaptation, Ocular, Color Perception
- Published
- 1965
- Full Text
- View/download PDF
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