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Meienhofer J, Patel RP. Synthesis of an actinomycin analog with substituted lactone oxygens (1',1'-bis(L-,-diaminopropionic acid))-actinomycin C (C 1). INTERNATIONAL JOURNAL OF PROTEIN RESEARCH 2009; 3:347-50. [PMID: 5289931 DOI: 10.1111/j.1399-3011.1971.tb01729.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Pandya VM, Patel DJ, Patel JK, Patel RP. Formulation, Characterization, and Optimization of Fast-Dissolve Tablets Containing Celecoxib Solid Dispersion. DISSOLUT TECHNOL 2009. [DOI: 10.14227/dt160409p22] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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128
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Shaik SS, Soltau TD, Chaturvedi G, Totapally B, Hagood JS, Andrews WW, Athar M, Voitenok NN, Killingsworth CR, Patel RP, Fallon MB, Maheshwari A. Low intensity shear stress increases endothelial ELR+ CXC chemokine production via a focal adhesion kinase-p38{beta} MAPK-NF-{kappa}B pathway. J Biol Chem 2008; 284:5945-55. [PMID: 19117939 DOI: 10.1074/jbc.m807205200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
CXC chemokines with a glutamate-leucine-arginine (ELR) tripeptide motif (ELR(+) CXC chemokines) play an important role in leukocyte trafficking into the tissues. For reasons that are not well elucidated, circulating leukocytes are recruited into the tissues mainly in small vessels such as capillaries and venules. Because ELR(+) CXC chemokines are important mediators of endothelial-leukocyte interaction, we compared chemokine expression by microvascular and aortic endothelium to investigate whether differences in chemokine expression by various endothelial types could, at least partially, explain the microvascular localization of endothelial-leukocyte interaction. Both in vitro and in vivo models indicate that ELR(+) CXC chemokine expression is higher in microvascular endothelium than in aortic endothelial cells. These differences can be explained on the basis of the preferential activation of endothelial chemokine production by low intensity shear stress. Low shear activated endothelial ELR(+) CXC chemokine production via cell surface heparan sulfates, beta(3)-integrins, focal adhesion kinase, the mitogen-activated protein kinase p38beta, mitogen- and stress-associated protein kinase-1, and the transcription factor.
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Patel NA, Patel NJ, Patel RP. Formulation and Evaluation of Curcumin Gel for Topical Application. Pharm Dev Technol 2008; 14:80-9. [DOI: 10.1080/10837450802409438] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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130
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Patel RP, Kolon TF, Huff DS, Carr MC, Zderic SA, Canning DA, Snyder HM. Cryptorchid testis histopathology in myelomeningocele patients. J Pediatr Urol 2008; 4:434-7. [PMID: 18644747 DOI: 10.1016/j.jpurol.2008.05.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Accepted: 05/21/2008] [Indexed: 10/21/2022]
Abstract
PURPOSE Cryptorchidism occurs in 25% of boys with myelomeningocele (MMC) compared to 3% of the general population. Testicular biopsy histopathology correlates with future sperm counts. We studied testicular histology in boys with cryptorchidism and MMC to investigate if the MMC influences histological findings. MATERIALS AND METHODS The study group consisted of six patients with MMC and undescended testis (UDT) who underwent orchiopexy and bilateral testis biopsy. Twelve testicular biopsies from six patients were compared to 40 biopsies from 20 UDT-only controls. Total germ cell count per tubule (TGC/T) and the percentage of adult dark spermatogonia (%Ad) in undescended and contralateral descended testes from the patients were compared with controls. RESULTS In the study group, two had total absence of germ cells (TGC/T=0) and three had severely reduced germ cells (TGC/T<0.2). Four had total absence of Ad spermatogonia and the remaining two had severely reduced Ad spermatogonia (%Ad=5). The mean TGC/T and %Ad in patients with UDT and MMC were conspicuously lower than controls. The differences did not reach statistical significance (P=0.09-0.29). CONCLUSION These results suggest that patients with both MMC and UDT have a more severe reduction in total number and more severely delayed maturation of germ cells than do patients with UDT alone. With only six patients in this study, there was not the power to detect statistical significance. In addition to the reproductive problems due to erection and ejaculatory dysfunction in patients with MMC, this severe testicular histopathology may increase the risk of subfertility.
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Patel RP, Patel MM. Physicochemical Characterization and Dissolution Study of Solid Dispersions of Lovastatin with Polyethylene Glycol 4000 and Polyvinylpyrrolidone K30. Pharm Dev Technol 2008; 12:21-33. [PMID: 17484141 DOI: 10.1080/10837450601166510] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Solid dispersions in water-soluble carriers have attracted considerable interest as a means of improving the dissolution rate, and hence possibly bioavailability, of a range of hydrophobic drugs. The aim of the present study was to improve the solubility and dissolution rate of a poorly water-soluble drug, Lovastatin, by a solid dispersion technique. Solid dispersions were prepared by using polyethylene glycol 4000 (PEG 4000) and polyvinylpyrrolidone K30 (PVP K30) in different drug-to-carrier ratios. Dispersions with PEG 4000 were prepared by fusion-cooling and solvent evaporation, whereas dispersions containing PVP K30 were prepared by solvent evaporation technique. These new formulations were characterized in the liquid state by phase solubility studies and in the solid state by differential scanning calorimetry, X-ray powder diffraction, and FT-IR spectroscopy. The aqueous solubility of Lovastatin was favored by the presence of both polymers. The negative values of the Gibbs free energy and enthalpy of transfer explained the spontaneous transfer from pure water to the aqueous polymer environment. Solid-state characterization indicated Lovastatin was present as amorphous material and entrapped in polymer matrix. In contrast to the very slow dissolution rate of pure Lovastatin, the dispersion of the drug in the polymers considerably enhanced the dissolution rate. This can be attributed to improved wettability and dispersibility, as well as decrease of the crystalline and increase of the amorphous fraction of the drug. Solid dispersion prepared with PVP showed the highest improvement in wettability and dissolution rate of Lovastatin. Even physical mixture of Lovastatin prepared with both polymers also showed better dissolution profile than that of pure Lovastatin. Tablets containing solid dispersion prepared with PEG and PVP showed significant improvement in the release profile Lovastatin compared with tablets containing Lovastatin without PEG or PVP.
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Liu Y, Chacko BK, Ricksecker A, Shingarev R, Andrews E, Patel RP, Lang JD. Modulatory effects of hypercapnia on in vitro and in vivo pulmonary endothelial-neutrophil adhesive responses during inflammation. Cytokine 2008; 44:108-17. [PMID: 18713668 DOI: 10.1016/j.cyto.2008.06.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2007] [Revised: 05/17/2008] [Accepted: 06/27/2008] [Indexed: 01/11/2023]
Abstract
Reducing tidal volume as a part of a protective ventilation strategy may result in hypercapnia. In this study, we focused on the influence of hypercapnia on endothelial-neutrophil responses in models of inflammatory-stimulated human pulmonary microvascular endothelial cells (HMVEC) and in an animal model of lipopolysaccharide (LPS)-induced acute lung injury. Neutrophil adhesion and adhesion molecules expression and nuclear factor-kappaB (NF-kappaB) were analyzed in TNF-alpha and LPS-treated HMVEC exposed to either eucapnia or hypercapnia. In the in vivo limb, bronchoalveolar lavage fluid cell counts and differentials, adhesion molecule and chemokine expression were assessed in LPS-treated rabbits ventilated with either low tidal volume ventilation and eucapnia or hypercapnia. In both the in vitro and in vivo models, hypercapnia significantly increased neutrophil adhesion and adhesion molecule expression compared to eucapnia. Activity of NF-kappaB was significantly enhanced by hypercapnia in the in vitro experiments. IL-8 expression was greatest both in vitro and in vivo under conditions of hypercapnia and concomitant inflammation. CD11a expression was greatest in isolated human neutrophils exposed to hypercapnia+LPS. Our results demonstrate that endothelial-neutrophil responses per measurement of fundamental molecules of adhesion are significantly increased during hypercapnia and that hypercapnia mimics conditions of eucapnia+inflammation.
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Isbell TS, Sun CW, Wu LC, Teng X, Vitturi DA, Branch BG, Kevil CG, Peng N, Wyss JM, Ambalavanan N, Schwiebert L, Ren J, Pawlik KM, Renfrow MB, Patel RP, Townes TM. SNO-hemoglobin is not essential for red blood cell-dependent hypoxic vasodilation. Nat Med 2008; 14:773-7. [PMID: 18516054 DOI: 10.1038/nm1771] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2007] [Accepted: 04/09/2008] [Indexed: 01/05/2023]
Abstract
The coupling of hemoglobin sensing of physiological oxygen gradients to stimulation of nitric oxide (NO) bioactivity is an established principle of hypoxic blood flow. One mechanism proposed to explain this oxygen-sensing-NO bioactivity linkage postulates an essential role for the conserved Cys93 residue of the hemoglobin beta-chain (betaCys93) and, specifically, for S-nitrosation of betaCys93 to form S-nitrosohemoglobin (SNO-Hb). The SNO-Hb hypothesis, which conceptually links hemoglobin and NO biology, has been debated intensely in recent years. This debate has precluded a consensus on physiological mechanisms and on assessment of the potential role of SNO-Hb in pathology. Here we describe new mouse models that exclusively express either human wild-type hemoglobin or human hemoglobin in which the betaCys93 residue is replaced with alanine to assess the role of SNO-Hb in red blood cell-mediated hypoxic vasodilation. Substitution of this residue, precluding hemoglobin S-nitrosation, did not change total red blood cell S-nitrosothiol abundance but did shift S-nitrosothiol distribution to lower molecular weight species, consistent with the loss of SNO-Hb. Loss of betaCys93 resulted in no deficits in systemic or pulmonary hemodynamics under basal conditions and, notably, did not affect isolated red blood cell-dependent hypoxic vasodilation. These results demonstrate that SNO-Hb is not essential for the physiologic coupling of erythrocyte deoxygenation with increased NO bioactivity in vivo.
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Casale P, Patel RP, Kolon TF. Nerve Sparing Robotic Extravesical Ureteral Reimplantation. J Urol 2008; 179:1987-9; discussion 1990. [DOI: 10.1016/j.juro.2008.01.062] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Indexed: 10/22/2022]
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135
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Gladwin MT, Patel RP. The Role of Red Blood Cells and Hemoglobin–Nitric Oxide Interactions on Blood Flow. Am J Respir Cell Mol Biol 2008; 38:125-6. [DOI: 10.1165/rcmb.2007-0006ed] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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136
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Patel RP, Patel DJ, Bhimani DB, Patel JK. Physicochemical Characterization and Dissolution Study of Solid Dispersions of Furosemide with Polyethylene Glycol 6000 and Polyvinylpyrrolidone K30. DISSOLUT TECHNOL 2008. [DOI: 10.14227/dt150308p17] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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137
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Patel RP, Casale P. Robotic pediatric urology. MINERVA UROL NEFROL 2007; 59:425-430. [PMID: 17947960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The minimally invasive surgery using robotic assistance is evolving fast in the field of pediatric urology. The freedom afforded by these surgical actuators is real and here to stay. The da Vinci surgical system (Intuitive Surgical, Sunnyvale, CA, USA) provides delicate manipulation, coalesced with three-dimensional visualization and a superior magnification. It has bridged the gap between laparoscopy and open surgery. Nonetheless, it should be made clear that in case of robotic malfunction laparoscopic skills are of paramount importance. Robotic pediatric urologic procedures such as pyeloplasty, ureteral reimplantation, partial or total nephrectomy with or without ureteral stump removal are now done on a regular basis at select centers offering robotic expertise. Reconstructive surgeries such as appendico-vesicostomy can be performed, however, such complex surgeries are still in their infancy.
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Lang JD, Teng X, Chumley P, Crawford JH, Isbell TS, Chacko BK, Liu Y, Jhala N, Crowe DR, Smith AB, Cross RC, Frenette L, Kelley EE, Wilhite DW, Hall CR, Page GP, Fallon MB, Bynon JS, Eckhoff DE, Patel RP. Inhaled NO accelerates restoration of liver function in adults following orthotopic liver transplantation. J Clin Invest 2007; 117:2583-91. [PMID: 17717604 PMCID: PMC1950460 DOI: 10.1172/jci31892] [Citation(s) in RCA: 168] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2007] [Accepted: 06/12/2007] [Indexed: 12/13/2022] Open
Abstract
Ischemia/reperfusion (IR) injury in transplanted livers contributes to organ dysfunction and failure and is characterized in part by loss of NO bioavailability. Inhalation of NO is nontoxic and at high concentrations (80 ppm) inhibits IR injury in extrapulmonary tissues. In this prospective, blinded, placebo-controlled study, we evaluated the hypothesis that administration of inhaled NO (iNO; 80 ppm) to patients undergoing orthotopic liver transplantation inhibits hepatic IR injury, resulting in improved liver function. Patients were randomized to receive either placebo or iNO (n = 10 per group) during the operative period only. When results were adjusted for cold ischemia time and sex, iNO significantly decreased hospital length of stay, and evaluation of serum transaminases (alanine transaminase, aspartate aminotransferase) and coagulation times (prothrombin time, partial thromboplastin time) indicated that iNO improved the rate at which liver function was restored after transplantation. iNO did not significantly affect changes in inflammatory markers in liver tissue 1 hour after reperfusion but significantly lowered hepatocyte apoptosis. Evaluation of circulating NO metabolites indicated that the most likely candidate transducer of extrapulmonary effects of iNO was nitrite. In summary, this study supports the clinical use of iNO as an extrapulmonary therapeutic to improve organ function following transplantation.
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139
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Sha X, Isbell TS, Patel RP, Day CS, King SB. Hydrolysis of acyloxy nitroso compounds yields nitroxyl (HNO). J Am Chem Soc 2007; 128:9687-92. [PMID: 16866522 DOI: 10.1021/ja062365a] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Nitroxyl (HNO/NO(-)), the reduced form of nitric oxide, has gained attention based on its separate chemistry and biology from nitric oxide. The inherent reactivity of HNO requires new and mechanistically unique donors for the detailed study of HNO chemistry and biology. Oxidation of cyclohexanone oxime with lead tetraacetate yields 1-nitrosocyclohexyl acetate, whereas oxidation of oximes in the presence of excess carboxylic acid gives various acyloxy nitroso compounds. These bright blue compounds exist as monomers as indicated by their infrared, proton, and carbon NMR spectra, and X-ray crystallographic analysis reveals the nitroso groups possess a "nitroxyl-like" bent configuration. Hydrolysis of these compounds produces nitrous oxide, the dimerization and dehydration product of HNO, and provides evidence for the intermediacy of HNO. Both thiols and oxidative metal complexes inhibit nitrous oxide formation. Hydrolysis of these compounds in the presence of ferric heme complexes forms ferrous nitrosyl complexes providing further evidence for the intermediacy of HNO. Kinetic analysis shows that the rate of hydrolysis depends on pH and the structure of the acyl group of the acyloxy nitroso compound. These compounds relax pre-constricted rat aortic rings similar to known HNO donors. Together, these results identify acyloxy nitroso compounds as a new class of HNO donors.
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140
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Senthilkumar A, Smith RD, Khitha J, Arora N, Veerareddy S, Langston W, Chidlow JH, Barlow SC, Teng X, Patel RP, Lefer DJ, Kevil CG. Sildenafil Promotes Ischemia-Induced Angiogenesis Through a PKG-Dependent Pathway. Arterioscler Thromb Vasc Biol 2007; 27:1947-54. [PMID: 17585066 DOI: 10.1161/atvbaha.107.147421] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Peripheral artery disease (PAD) is a prevalent cardiovascular disorder that results in tissue ischemia which can progress to critical limb ischemia. Restoration of tissue perfusion in the setting of chronic ischemia through stimulation of arteriogenesis and angiogenesis remains a key therapeutic target for PAD. However, experimental therapeutics, including growth factor and gene therapy, have had little clinical success indicating the need for a better understanding of molecular pathways required for therapeutic angiogenesis. METHODS AND RESULTS Here we report that phosphodiesterase-5 inhibition by sildenafil significantly increases vascular perfusion, tissue blood flow, and vascular density during chronic ischemia of the mouse hind limb. Importantly, sildenafil therapy did not alter any of these parameters in nonischemic limbs. Sildenafil increased tissue cGMP levels independently of increases in nitric oxide production, and sildenafil therapy stimulated angiogenesis in ischemic limbs of eNOS-/- and iNOS-/- mice. Lastly, sildenafil-mediated angiogenic activity was blocked by inhibition of protein kinase G using the PKG antagonist DT-3. CONCLUSIONS These data demonstrate that sildenafil therapy results in increased angiogenic activity through a PKG-dependent pathway that is independent of nitric oxide production or NOS activity and identify the angiogenic therapeutic potential of sildenafil for critical limb ischemia.
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141
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Isbell TS, Gladwin MT, Patel RP. Hemoglobin oxygen fractional saturation regulates nitrite-dependent vasodilation of aortic ring bioassays. Am J Physiol Heart Circ Physiol 2007; 293:H2565-72. [PMID: 17766472 DOI: 10.1152/ajpheart.00759.2007] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nitrite reacts with deoxyhemoglobin to generate nitric oxide (NO). This reaction has been proposed to contribute to nitrite-dependent vasodilation in vivo and potentially regulate physiological hypoxic vasodilation. Paradoxically, while deoxyhemoglobin can generate NO via nitrite reduction, both oxyhemoglobin and deoxyhemoglobin potently scavenge NO. Furthermore, at the very low O(2) tensions required to deoxygenate cell-free hemoglobin solutions in aortic ring bioassays, surprisingly low doses of nitrite can be reduced to NO directly by the blood vessel, independent of the presence of hemoglobin; this makes assessments of the role of hemoglobin in the bioactivation of nitrite difficult to characterize in these systems. Therefore, to study the O(2) dependence and ability of deoxhemoglobin to generate vasodilatory NO from nitrite, we performed full factorial experiments of oxyhemoglobin, deoxyhemoglobin, and nitrite and found a highly significant interaction between hemoglobin deoxygenation and nitrite-dependent vasodilation (P < or = 0.0002). Furthermore, we compared the effect of hemoglobin oxygenation on authentic NO-dependent vasodilation using a NONOate NO donor and found that there was no such interaction, i.e., both oxyhemoglobin and deoxyhemoglobin inhibited NO-mediated vasodilation. Finally, we showed that another NO scavenger, 2-carboxyphenyl-4,4-5,5-tetramethylimidazoline-1-oxyl-3-oxide, inhibits nitrite-dependent vasodilation under normoxia and hypoxia, illustrating the uniqueness of the interaction of nitrite with deoxyhemoglobin. While both oxyhemoglobin and deoxyhemoglobin potently inhibit NO, deoxyhemoglobin exhibits unique functional duality as an NO scavenger and nitrite-dependent NO generator, suggesting a model in which intravascular NO homeostasis is regulated by a balance between NO scavenging and NO generation that is dynamically regulated by hemoglobin's O(2) fractional saturation and allosteric nitrite reductase activity.
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Kumar A, Toledo JC, Patel RP, Lancaster JR, Steyn AJC. Mycobacterium tuberculosis DosS is a redox sensor and DosT is a hypoxia sensor. Proc Natl Acad Sci U S A 2007; 104:11568-73. [PMID: 17609369 PMCID: PMC1906723 DOI: 10.1073/pnas.0705054104] [Citation(s) in RCA: 243] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A fundamental challenge to the study of oxidative stress responses of Mycobacterium tuberculosis (Mtb) is to understand how the protective host molecules are sensed and relayed to control bacilli gene expression. The genetic response of Mtb to hypoxia and NO is controlled by the sensor kinases DosS and DosT and the response regulator DosR through activation of the dormancy/NO (Dos) regulon. However, the regulatory ligands of DosS and DosT and the mechanism of signal sensing were unknown. Here, we show that both DosS and DosT bind heme as a prosthetic group and that DosS is rapidly autooxidized to attain the met (Fe3+) form, whereas DosT exists in the O2-bound (oxy) form. EPR and UV-visible spectroscopy analysis showed that O2, NO, and CO are ligands of DosS and DosT. Importantly, we demonstrate that the oxidation or ligation state of the heme iron modulates DosS and DosT autokinase activity and that ferrous DosS, and deoxy DosT, show significantly increased autokinase activity compared with met DosS and oxy DosT. Our data provide direct proof that DosS functions as a redox sensor, whereas DosT functions as a hypoxia sensor, and that O2, NO, and CO are modulatory ligands of DosS and DosT. Finally, we identified a third potential dormancy signal, CO, that induces the Mtb Dos regulon. We conclude that Mtb has evolved finely tuned redox and hypoxia-mediated sensing strategies for detecting O2, NO, and CO. Data presented here establish a paradigm for understanding the mechanism of bacilli persistence.
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143
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Tang L, Luo B, Patel RP, Ling Y, Zhang J, Fallon MB. Modulation of pulmonary endothelial endothelin B receptor expression and signaling: implications for experimental hepatopulmonary syndrome. Am J Physiol Lung Cell Mol Physiol 2007; 292:L1467-72. [PMID: 17337507 PMCID: PMC2825024 DOI: 10.1152/ajplung.00446.2006] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The hepatopulmonary syndrome (HPS) results from intrapulmonary vasodilation in the setting of cirrhosis and portal hypertension. In experimental HPS, pulmonary endothelial endothelin B (ET(B)) receptor overexpression and increased circulating endothelin-1 (ET-1) contribute to vasodilation through enhanced endothelial nitric oxide synthase (eNOS)-derived nitric oxide (NO) production. In both experimental cirrhosis and prehepatic portal hypertension, ET(B) receptor overexpression correlates with increased vascular shear stress, a known modulator of ET(B) receptor expression. We investigated the mechanisms of pulmonary endothelial ET(B) receptor-mediated eNOS activation by ET-1 in vitro and in vivo. The effect of shear stress on ET(B) receptor expression was assessed in rat pulmonary microvascular endothelial cells (RPMVECs). The consequences of ET(B) receptor overexpression on ET-1-dependent ET(B) receptor-mediated eNOS activation were evaluated in RPMVECs and in prehepatic portal hypertensive animals exposed to exogenous ET-1. Laminar shear stress increased ET(B) receptor expression in RPMVECs without altering mRNA stability. Both shear-mediated and targeted overexpression of the ET(B) receptor enhanced ET-1-mediated ET(B) receptor-dependent eNOS activation in RPMVECs through Ca(2+)-mediated signaling pathways and independent of Akt activation. In prehepatic portal hypertensive animals relative to control, ET-1 administration also activated eNOS independent of Akt activation and triggered HPS. These findings support that increased pulmonary microvascular endothelial ET(B) receptor expression modulates ET-1-mediated eNOS activation, independent of Akt, and contributes to the development of HPS.
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Langston W, Chidlow JH, Booth BA, Barlow SC, Lefer DJ, Patel RP, Kevil CG. Regulation of endothelial glutathione by ICAM-1 governs VEGF-A-mediated eNOS activity and angiogenesis. Free Radic Biol Med 2007; 42:720-9. [PMID: 17291995 PMCID: PMC1855188 DOI: 10.1016/j.freeradbiomed.2006.12.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2006] [Revised: 11/30/2006] [Accepted: 12/13/2006] [Indexed: 10/23/2022]
Abstract
Previous studies suggest that inflammatory cell adhesion molecules may modulate endothelial cell migration and angiogenesis through unknown mechanisms. Using a combination of in vitro and in vivo approaches, herein we reveal a novel redox-sensitive mechanism by which ICAM-1 modulates endothelial GSH that controls VEGF-A-induced eNOS activity, endothelial chemotaxis, and angiogenesis. In vivo disk angiogenesis assays showed attenuated VEGF-A-mediated angiogenesis in ICAM-1(-/-) mice. Moreover, VEGF-A-dependent chemotaxis, eNOS phosphorylation, and nitric oxide production were impaired in ICAM-1(-/-) mouse aortic endothelial cells (MAEC) compared to WT MAEC. Decreasing intracellular GSH in ICAM-1(-/-) MAEC to levels observed in WT MAEC with 150 microM buthionine sulfoximine restored VEGF-A responses. Conversely, GSH supplementation of WT MAEC with 5 mM glutathione ethyl ester mimicked defects observed in ICAM-1(-/-) cells. Deficient angiogenic responses in ICAM-1(-/-) cells were associated with increased expression of the lipid phosphatase PTEN, consistent with antagonism of signaling pathways leading to eNOS activation. PTEN expression was also sensitive to GSH status, decreasing or increasing in proportion to intracellular GSH concentrations. These data suggest a novel role for ICAM-1 in modulating VEGF-A-induced angiogenesis and eNOS activity through regulation of PTEN expression via modulation of intracellular GSH status.
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Chacko BK, Chandler RT, D'Alessandro TL, Mundhekar A, Khoo NKH, Botting N, Barnes S, Patel RP. Anti-inflammatory effects of isoflavones are dependent on flow and human endothelial cell PPARgamma. J Nutr 2007; 137:351-6. [PMID: 17237310 DOI: 10.1093/jn/137.2.351] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The mechanisms by which isoflavones protect against inflammatory vascular disease remain unclear. Our previous observations suggest that one mechanism involves inhibition of monocyte-endothelial cell interactions in a process that is absolutely dependent on flow. The molecular mechanisms involved and the effects of structurally distinct isoflavones on this process are not known and are investigated herein. Using static and flow-dependent monocyte adhesion assays, our data show that exposure of endothelial cells to biologically relevant concentrations of isoflavones inhibits subsequent TNF-alpha induced monocyte adhesion only during flow. This inhibition involved activating endothelial PPARgamma by stimulating promoter sequences containing the PPARgamma response element by isoflavones and attenuating antiadhesive effects by siRNA targeting of PPARgamma. A comparison of structurally distinct isoflavones suggested a critical role for the A-ring. Using chlorinated derivatives of daidzein, a key structural requirement for PPARgamma agonist activity appears to be the presence of the 7-OH group and the lack of chlorine at the 6- or 8-positions in the A-ring. Collectively, these data support 1) a novel flow-dependent anti-inflammatory mechanism for PPARgamma ligands in vascular endothelial cells and 2) exemplify the current concepts of nutrients modulating disease via regulating specific cell signaling pathways.
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146
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Koenitzer JR, Isbell TS, Patel HD, Benavides GA, Dickinson DA, Patel RP, Darley-Usmar VM, Lancaster JR, Doeller JE, Kraus DW. Hydrogen sulfide mediates vasoactivity in an O2-dependent manner. Am J Physiol Heart Circ Physiol 2007; 292:H1953-60. [PMID: 17237242 DOI: 10.1152/ajpheart.01193.2006] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hydrogen sulfide (H(2)S) has recently been shown to have a signaling role in vascular cells. Similar to nitric oxide (NO), H(2)S is enzymatically produced by amino acid metabolism and can cause posttranslational modification of proteins, particularly at thiol residues. Molecular targets for H(2)S include ATP-sensitive K(+) channels, and H(2)S may interact with NO and heme proteins such as cyclooxygenase. It is well known that the reactions of NO in the vasculature are O(2) dependent, but this has not been addressed in most studies designed to elucidate the role of H(2)S in vascular function. This is important, since H(2)S reactions can be dramatically altered by the high concentrations of O(2) used in cell culture and organ bath experiments. To test the hypothesis that the effects of H(2)S on the vasculature are O(2) dependent, we have measured real-time levels of H(2)S and O(2) in respirometry and vessel tension experiments, as well as the associated vascular responses. A novel polarographic H(2)S sensor developed in our laboratory was used to measure H(2)S levels. Here we report that, in rat aorta, H(2)S concentrations that mediate rapid contraction at high O(2) levels cause rapid relaxation at lower physiological O(2) levels. At high O(2), the vasoconstrictive effect of H(2)S suggests that it may not be H(2)S per se but, rather, a putative vasoactive oxidation product that mediates constriction. These data are interpreted in terms of the potential for H(2)S to modulate vascular tone in vivo.
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147
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Pruitt HM, Langston W, Kevil CG, Patel RP. ICAM-1 cross-linking stimulates endothelial glutathione synthesis. Antioxid Redox Signal 2007; 9:159-64. [PMID: 17115895 DOI: 10.1089/ars.2007.9.159] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
What mechanisms regulate endothelial glutathione (GSH) during inflammation? Addressing this question is critical in understanding mechanisms leading to endothelial dysfunction and cardiovascular disease. Herein, the authors show data that support the hypothesis that the intercellular cell adhesion molecule-1 (ICAM-1) regulates GSH. Ligating either constitutive or induced ICAM-1 on the endothelial surface, or exposing endothelial cells to soluble ICAM-1, increases GSH concentrations. ICAM-1 is important in mediating leukocyte adhesion and modulates endothelial signaling pathways important in controlling transmigration. The present data underscore a novel function for ICAM-1 in modulating GSH metabolism and raise the hypothesis that this adhesion molecule controls endothelial redox status under basal and inflammatory conditions.
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148
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Huynh TN, Chacko BK, Teng X, Brott BC, Allon M, Kelpke SS, Thompson JA, Patel RP, Anayiotos AS. Effects of venous needle turbulence during ex vivo hemodialysis on endothelial morphology and nitric oxide formation. J Biomech 2006; 40:2158-66. [PMID: 17161843 DOI: 10.1016/j.jbiomech.2006.10.028] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2006] [Accepted: 10/26/2006] [Indexed: 10/23/2022]
Abstract
Arteriovenous grafts used for hemodialysis frequently develop intimal hyperplasia (IH), which ultimately leads to graft failure. Although the turbulent jet from the dialysis needle may contribute to vessel wall injury, its role in the pathogenesis of IH is relatively unexplored. In the current study, using bovine aortic endothelial cells (BAEC) cultured on the inner surface of a compliant tube, we evaluated the effects of simulated hemodialysis conditions on morphology and nitric oxide (NO) production. The flows via the graft and needle were 500 ml/min (Reynolds number=819) and 100ml/min (Reynolds number=954), respectively. In the presence of the needle jet for 6h, 19.3% (+/-1.53%) of BAEC were sheared off, whereas no loss of BAEC was observed in the presence of graft flow alone (P<0.05). In the presence of graft flow alone, assessment of cell orientation by the Saltykov method revealed that BAEC were oriented along the flow direction. This alignment, however, was lost in the presence of needle flow. Finally, NO production was also significantly decreased in the presence of the needle flow compared to the presence of graft flow alone (16+/-3.1 vs 34.7+/-1.9 nmol/10(6)cells/h, P<0.05). NO is a key player in vascular homeostasis mechanisms modulating vasomotor tone, inhibiting inflammation and smooth muscle cell proliferation. Thus, the loss of NO signaling and the loss of endothelial integrity caused by needle jet turbulence may contribute to the cascade of events leading to IH formation during hemodialysis.
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149
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Zhang J, Ling Y, Tang L, Luo B, Chacko BK, Patel RP, Fallon MB. Pentoxifylline attenuation of experimental hepatopulmonary syndrome. J Appl Physiol (1985) 2006; 102:949-55. [PMID: 17110505 PMCID: PMC2822394 DOI: 10.1152/japplphysiol.01048.2006] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Hepatopulmonary syndrome (HPS) following rat common bile duct ligation results from pulmonary molecular changes that may be influenced by circulating TNF-alpha and increased vascular shear stress, through activation of NF-kappaB or Akt. Increased pulmonary microvascular endothelin B (ET(B)) receptor and endothelial nitric oxide synthase (eNOS) levels contribute to nitric oxide production and the development of experimental HPS. Pentoxifylline (PTX), a phosphodiesterase and nonspecific TNF-alpha inhibitor, ameliorates experimental HPS when begun before hepatic injury. However, how PTX influences the molecular events associated with initiation of experimental HPS after liver injury is established is unknown. We assessed the effects of PTX on the molecular and physiological features of HPS in vivo and on shear stress or TNF-alpha-mediated events in rat pulmonary microvascular endothelial cells in vitro. PTX significantly improved HPS without altering portal or systemic hemodynamics and downregulated pulmonary ET(B) receptor levels and eNOS expression and activation. These changes were associated with a reduction in circulating TNF levels and NF-kappaB activation and complete inhibition of Akt activation. In rat pulmonary microvascular endothelial cells, PTX inhibited shear stress-induced ET(B) receptor and eNOS expression and eNOS activation. These effects were also associated with inhibition of Akt activation and were reproduced by wortmanin. In contrast, TNF-alpha had no effects on endothelial ET(B) and eNOS alterations in vitro. PTX has direct effects in the pulmonary microvasculature, likely mediated through Akt inhibition, that ameliorate experimental HPS.
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150
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Cui T, Schopfer FJ, Zhang J, Chen K, Ichikawa T, Baker PRS, Batthyany C, Chacko BK, Feng X, Patel RP, Agarwal A, Freeman BA, Chen YE. Nitrated fatty acids: Endogenous anti-inflammatory signaling mediators. J Biol Chem 2006; 281:35686-98. [PMID: 16887803 PMCID: PMC2169500 DOI: 10.1074/jbc.m603357200] [Citation(s) in RCA: 276] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nitroalkene derivatives of linoleic acid (LNO2) and oleic acid (OA-NO2) are present; however, their biological functions remain to be fully defined. Herein, we report that LNO2 and OA-NO2 inhibit lipopolysaccharide-induced secretion of proinflammatory cytokines in macrophages independent of nitric oxide formation, peroxisome proliferator-activated receptor-gamma activation, or induction of heme oxygenase-1 expression. The electrophilic nature of fatty acid nitroalkene derivatives resulted in alkylation of recombinant NF-kappaB p65 protein in vitro and a similar reaction with p65 in intact macrophages. The nitroalkylation of p65 by fatty acid nitroalkene derivatives inhibited DNA binding activity and repressed NF-kappaB-dependent target gene expression. Moreover, nitroalkenes inhibited endothelial tumor necrosis factor-alpha-induced vascular cell adhesion molecule 1 expression and monocyte rolling and adhesion. These observations indicate that nitroalkenes such as LNO2 and OA-NO2, derived from reactions of unsaturated fatty acids and oxides of nitrogen, are a class of endogenous anti-inflammatory mediators.
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