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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The hypertensive effect observed with most cell-free haemoglobins has been proposed to result from NO scavenging. However, a newly developed PEG [poly(ethylene glycol)]-conjugated haemoglobin, MalPEG-Hb [maleimide-activated PEG-conjugated haemoglobin], is non-hypertensive with unique physicochemical properties: high O2 affinity, low co-operativity and large molecular radius. It is therefore of interest to compare the ligand-binding properties of MalPEG-Hb with unmodified cell-free HbA (stroma-free human haemoglobin). NO association rates for deoxy and oxyMalPEG-Hb and HbA were found to be identical. These results confirm the lack of correlation between hypertension and NO for a similar modified haemoglobin with high molecular radius and low p50 (pO2 at which haemoglobin is half-saturated with O2) [Rohlfs, Bruner, Chiu, Gonzales, Gonzales, Magde, Magde, Vandegriff and Winslow (1998) J. Biol. Chem. 273, 12128-12134]. The R-state O2 association kinetic constants were also the same for the two haemoglobins. However, even though the p50 of MalPEG-Hb is approx. half of that of HbA, the biphasic O2 dissociation rates measured at relatively high pO2 (150 Torr) were 2-fold higher, giving rise to a 2-fold lower R-state equilibrium association constant for MalPEG-Hb compared with HbA. Thus the O2 affinity of MalPEG-Hb is higher only at pO2 values lower than the intersection point of the O2 equilibrium curves for MalPEG-Hb and HbA. In summary, the present studies found similar rates of NO binding to HbA and MalPEG-Hb, eliminating the possibility that the lack of vasoactivity of MalPEG-Hb is simply the result of reduced molecular reactivity with NO. Alternatively, the unique O2-binding characteristics with low p50 and co-operativity suggest that the 'R-state' conformation of MalPEG-Hb is in a more T-state configuration and restricted from conformational change.
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PMID:Kinetics of NO and O2 binding to a maleimide poly(ethylene glycol)-conjugated human haemoglobin. 1517 10

Disturbed nitric oxide (NO) synthesis leads to development of endothelial dysfunction that plays a significant role in the pathogenesis of arterial hypertension. The presence of various compounds of haemoglobin with NO can affect haemoglobin-oxygen affinity of the whole blood. Methaemoglobin and S-nitrosohaemoglobin increase it, whereas nitrosyl-haemoglobin decreases. The aim of this study was to investigate the blood oxygen transport indices and to assess the endothelial function in patients with arterial hypertension. The patients with mild hypertension had a 4.47% increased actual p50 (the blood pO(2) corresponding to its 50% oxygen saturation) (P<0.05), a diminished pO(2) (P<0.05), and a raised pCO(2) (P<0.01) as compared with the controls. The patients with severe hypertension had decreased pO(2) and pH, and actual p50 was reduced by 3.03% (P<0.05), which reflects a more pronounced oxyhaemoglobin dissociation curve shift leftwards. These changes can be assessed as a blood oxygen transport decompensation that enhanced tissue hypoxia. The results of our studies indicate that the endothelial dysfunction in patients with arterial hypertension leads to significant impairments in blood oxygen transport indices. The endothelium may be involved in development of the above blood oxygen transport impairments, since only sufficient amounts of NO maintain a normal blood flow and oxygen transport to tissues. The endothelial dysfunction leads to a disturbed production of different haemoglobin NO derivatives, which not only affects NO release at different sites of the arterial bed, but also haemoglobin-oxygen affinity and optimal blood oxygenation and deoxygenation in capillaries. These data support the notion that endothelial dysfunction may alter haemoglobin-oxygen affinity and tissue oxygen supply in vivo. Alternation of haemoglobin-oxygen supply may be involved in the pathogenesis of hypertension.
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PMID:Blood oxygen transport and endothelial dysfunction in patients with arterial hypertension. 1523 34

We investigated the role of angiotensin II in vascular and circulating inflammatory markers in spontaneously hypertensive rats (SHR). IL-1beta, IL-6, and TNF-alpha aortic mRNA expression and plasma levels were measured in adult SHR untreated or treated with the angiotensin II receptor antagonist candesartan (2 mg.kg(-1).day(-1)) or antihypertensive triple therapy (TT; in mg.kg(-1).day(-1): 20 hydralazine + 7 type 1 hydrochlorothiazide + 0.15 reserpine) for 10 wk. Likewise, aortic expression of NF-kappaB p50 subunit precursor p105 and its inhibitor (IkappaB) were measured. Age-matched Wistar-Kyoto rats (WKY) served as normotensive reference. High blood pressure levels were associated with increased (P < 0.05) aortic mRNA expression of IL-1beta, IL-6, and TNF-alpha. Hypertension was also accompanied by increased IL-1beta and IL-6 plasma levels. No differences were observed in circulating TNF-alpha levels between SHR and WKY. SHR presented elevated aortic mRNA expression of the transcription factor NF-kappaB and reduction in its inhibitor, IkappaB. Candesartan decreased (P < 0.05) blood pressure levels, aortic mRNA expression of IL-1beta, IL-6, and TNF-alpha, and (P < 0.05) IL-1beta and IL-6 plasma concentration. However, although arterial pressure decrease was comparable for the treatments, TT only partially reduced the increments in inflammatory markers. In fact, candesartan-treated rats showed significantly lower levels of circulating and vascular inflammatory markers than TT-treated animals. The treatments increased IkappaB mRNA expression similarly. However, only candesartan reduced NF-kappaB mRNA expression. In summary, 1) SHR presented a vascular inflammatory process; 2) angiotensin II, and increased hemodynamic forces associated with hypertension, seems to be involved in stimulation of inflammatory mediators through NF-kappaB system activation; and 3) reduction of inflammatory mediators produced by candesartan in SHR could be partially due to both downregulation of NF-kappaB and upregulation of IkappaB.
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PMID:Effect of AT1 receptor antagonism on vascular and circulating inflammatory mediators in SHR: role of NF-kappaB/IkappaB system. 1530 81

A new hemoglobin derivative, MP4, for use as a temporary oxygen-carrying plasma expander, has been prepared. The design of the molecule is based on novel criteria for optimized efficacy and safety, which include increased molecular radius, increased viscosity, increased oncotic pressure, and reduced p50. The chemical entity, MalPEG-Hb, is formulated at 4.2 g/dL in lactated Ringer's solution (MP4). It has a p50 of 5-6 mm Hg, oncotic pressure of 49 mm Hg and viscosity of 2.2 cPs. After 50% exchange transfusion with MP4, rats survive a 60% controlled hemorrhage in spite of total hemoglobin of 7.8 g/dL and plasma hemoglobin concentration of 1.6 g/dL. Although its binding affinity for NO is not different from that of purified hemoglobin A, it does not produce hypertension in a number of animal models and does not cause vasoconstriction in hamster microcirculation. Oxygen supply to tissue has been confirmed by direct observation in the hamster skinfold model, in which O2 release in precapillary and capillary vessels was quantified. The data demonstrate that the effectiveness of MP4 results from its ability to conserve O2 in precapillary vessels and release O2 in capillaries, thereby "targeting" O2 to hypoxic tissue. Preservation of functional capillary density and prevention of vasoconstriction further contribute to the effectiveness of this new formulation. MP4 is currently being tested in humans.
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PMID:MP4, a new nonvasoactive polyethylene glycol-hemoglobin conjugate. 1532 Sep 43

Nuclear factor kappa B (NFkappaB), commonly a proinflammatory transcription factor, is responsible for increasing transcription of the endothelial cell nitric oxide synthase (eNOS) in response to laminar shear stress. Nitric oxide (NO) production can be stimulated by shear, and NO is known to inhibit NFkappaB activation. We hypothesized that this inhibitory action of NO on NFkappaB activation serves as a negative feedback to inhibit NFkappaB activity and eNOS transcription. Exposure of bovine aortic endothelial cells to laminar shear stimulated steady state eNOS mRNA expression and eNOS promoter activity as measured using an eNOS promoter/CAT construct. These effects of shear were enhanced by the NOS inhibitor l-NAME and decreased by the NO-donor DPTA-NO by 30-50%. The NFkappaB inhibitor panepoxydone prevented the increase in eNOS mRNA caused by shear confirming a role of NFkappaB in this response. Shear stress stimulated a transient (30 min) nuclear translocation of the NFkappaB subunit p50. Treatment with l-NAME increased binding of the NFkappaB subunit p50 to consensus oligonucleotide-coated microtiter plates, while having only minimal effect on binding of p65, strongly suggesting that nitric oxide mainly inhibits p50 activation. Using the biotin switch method, we found that shear stress stimulates p50 nitrosylation and this was prevented by l-NAME. Moreover, transfection of endothelial cells with a vector encoding the C62S p50, a variant with a point mutation of the nitrosylation site C62, markedly increased nuclear translocation of p50 and doubled eNOS mRNA expression under shear stress compared to that observed in cells transfected with wild-type p50. We conclude that this interaction between shear, NFkappaB activation, NO production and NFkappaB inhibition represents a classical negative feedback loop, which prevents sustained activation of NFkappaB. In the absence of NO, shear stimulation of NFkappaB and eNOS transcription are enhanced. Our findings emphasize the critical role of NO in modulation of the endothelial cell inflammatory state. Several common diseases, including hypercholesteremia, hypertension and diabetes, are associated with eNOS dysfunction. Under these conditions, decreased NO availability may result in sustained activation of NFkappaB in response to shear and unrestrained endothelial inflammation.
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PMID:A negative feedback mechanism involving nitric oxide and nuclear factor kappa-B modulates endothelial nitric oxide synthase transcription. 1609 68

We investigated the role of nuclear factor kappaB (NF-kappaB) in the cytokine-mediated induction of cyclooxygenase-2 activity in the paraventricular nucleus of hypothalamus (PVN), a critical cardiovascular and autonomic center, in rats with heart failure (HF). Sprague-Dawley rats underwent coronary artery ligation to induce HF or sham surgery. HF rats were treated orally for 6 weeks with vehicle (tap water), the NF-kappaB inhibitor pyrrolidine dithiocarbamate (150 mg/kg per day), or the mineralocorticoid receptor antagonist eplerenone (30 mg/kg per day), which has been shown to reduce circulating proinflammatory cytokines in this model. Compared with sham surgery, HF rats had higher (P<0.05) levels of aldosterone, interleukin-1beta and norepinephrine in plasma and prostaglandin E2 in cerebrospinal fluid. In the PVN, NF-kappaB p50 precursor p105 mRNA increased, and mRNA for its inhibitor, IkappaB, decreased (P<0.05). Cyclooxygenase-2 mRNA and protein expression was increased in perivascular cells of the PVN. Both pyrrolidine dithiocarbamate and eplerenone reduced (P<0.05) p105 mRNA and increased IkappaB mRNA in PVN. Both also reduced (P<0.05) cyclooxygenase-2 mRNA and protein expression in PVN, cerebrospinal fluid prostaglandin E2, and plasma norepinephrine. Eplerenone, but not pyrrolidine dithiocarbamate, reduced plasma interleukin-1beta. Pyrrolidine dithiocarbamate and eplerenone had no effect on plasma aldosterone. The results suggest that activation of NF-kappaB is an intermediary step in cytokine-mediated induction of cyclooxygenase-2 in the PVN of HF rats. By enhancing access of prostaglandin E2 to hypothalamic neurons, this mechanism may contribute to augmented sympathetic nerve activity in HF.
Hypertension 2007 Mar
PMID:Increased cyclooxygenase-2 expression in hypothalamic paraventricular nucleus in rats with heart failure: role of nuclear factor kappaB. 1724 97

ANG II promotes inflammation through nuclear factor-kappaB (NF-kappaB)-mediated induction of cytokines and reactive oxygen species (ROS). The aim of the present study was to examine the effect of tetradecylthioacetic acid (TTA), a modified fatty acid, on NF-kappaB, proinflammatory markers, ROS, and nitric oxide (NO) production in two-kidney, one-clip (2K1C) hypertension. The 2K1C TTA-treated group had lower blood pressure (128 +/- 3 mmHg) compared with 2K1C nontreated (178 +/- 5 mmHg, P < 0.001). The p50 and p65 subunits of NF-kappaB were higher in the clipped kidney (0.44 +/- 0.01 and 0.22 +/- 0.01, respectively) compared with controls (0.25 +/- 0.03 and 0.12 +/- 0.02, respectively, P < 0.001). In the 2K1C TTA-treated group, these values were similar to control levels. The same pattern of response was seen in the nonclipped kidney. In 2K1C hypertension, cytokines plasma were higher than in control: TNF-alpha was 13.5 +/- 2 pg/ml (P < 0.03), IL-1beta was 58.8 +/- 10 pg/ml (P = 0.003), IL-6 was 210 +/- 33 pg/ml (P < 0.001), and monocyte chemoattractant protein-1 was 429 +/- 21 pg/ml (P = 0.04). In the 2K1C TTA-treated group, these values were similar to controls, and the same pattern was seen in the clipped kidney. Clipping increased 8-iso-PGF-2alpha (P < 0.01) and decreased NO production (P < 0.01 vs. control) in the urine. TTA treatment normalized these values. NO production was also lower in clipped and nonclipped kidney (P < 0.001). After TTA treatment, these values were similar to controls. The results indicate that TTA has a potent anti-inflammatory effect in 2K1C by inhibition of p50/p65 NF-kappaB subunit activation, reduction of cytokines production and ROS, and enhanced NO production.
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PMID:Tetradecylthioacetic acid prevents the inflammatory response in two-kidney, one-clip hypertension. 1803 69

Soluble guanylyl cyclase (sGC) is the principal receptor for NO and plays a ubiquitous role in regulating cellular function. This is exemplified in the cardiovascular system where sGC governs smooth muscle tone and growth, vascular permeability, leukocyte flux, and platelet aggregation. As a consequence, aberrant NO-sGC signaling has been linked to diseases including hypertension, atherosclerosis, and stroke. Despite these key (patho)physiological roles, little is known about the expressional regulation of sGC. To address this deficit, we have characterized the promoter activity of human alpha(1) and beta(1) sGC genes in a cell type relevant to cardiovascular (patho)physiology, primary human aortic smooth muscle cells. Luciferase reporter constructs revealed that the 0.3- and 0.5-kb regions upstream of the transcription start sites were optimal for alpha(1) and beta(1) sGC promoter activity, respectively. Deletion of consensus sites for c-Myb, GAGA, NFAT, NF-kappaB(p50), and CCAAT-binding factor(s) (CCAAT-BF) revealed that these are the principal transcription factors regulating basal sGC expression. In addition, under pro-inflammatory conditions, the effects of the strongest alpha(1) and beta(1) sGC repressors were enhanced, and enzyme expression and activity were reduced; in particular, NF-kappaB(p50) is pivotal in regulating enzyme expression under such conditions. NO itself also elicited a cGMP-independent negative feedback effect on sGC promoter activity that is mediated, in part, via CCAAT-BF activity. In sum, these data provide a systematic characterization of the promoter activity of human sGC alpha(1) and beta(1) subunits and identify key transcription factors that govern subunit expression under basal and pro-inflammatory (i.e. atherogenic) conditions and in the presence of ligand NO.
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PMID:Characterization of the human alpha1 beta1 soluble guanylyl cyclase promoter: key role for NF-kappaB(p50) and CCAAT-binding factors in regulating expression of the nitric oxide receptor. 1847

Pulmonary vascular remodeling, a major cause for the elevated pulmonary vascular resistance in patients with pulmonary arterial hypertension (PAH), is partially due to increased proliferation of pulmonary arterial smooth muscle cells (PASMC) in the media, resulting in vascular wall thickening. Platelet-derived growth factor (PDGF) is a potent mitogen that may be involved in the progression of PAH. Blockade of PDGF receptors has been demonstrated to have therapeutic potential for patients with severe pulmonary hypertension. Prednisolone is an immunosuppressant shown to have anti-inflammatory and antiproliferative effects on PASMC. This study was designed to investigate whether PDGF and prednisolone affect human PASMC proliferation by regulating the nuclear translocation of NF-kappaB (a transcription factor composed of 2 subunits, p50 and p65). Treatment of human PASMC with PDGF (10 ng/ml) significantly increased nuclear translocation of p50 and p65 subunits. Inhibition of NF-kappaB activation or nuclear translocation of p50/p65 significantly attenuated PDGF-induced PASMC proliferation (determined by [(3)H]thymidine incorporation). In the presence of prednisolone (200 microM), the PDGF-induced nuclear translocation of p50 and p65 subunits was markedly inhibited (P < 0.05 vs. the cells treated with PDGF alone). These results indicate that PDGF-induced nuclear translocation of NF-kappaB may play an important role in stimulating PASMC proliferation (and/or enhancing PASMC survival), whereas prednisolone may exert anti-inflammatory and antiproliferative effects on PASMC by inhibiting NF-kappaB nuclear translocation.
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PMID:Prednisolone inhibits PDGF-induced nuclear translocation of NF-kappaB in human pulmonary artery smooth muscle cells. 1870 31

Traumatic brain injury is a devastating neurological injury associated with significant morbidity and mortality. Medical therapies to limit cerebral edema, a cause of increased intracranial hypertension and poor clinical outcome, are largely ineffective, emphasizing the need for novel therapeutic approaches. In the present study, pre-treatment with curcumin (75, 150 mg/kg) or 30 min post-treatment with 300 mg/kg significantly reduced brain water content and improved neurological outcome following a moderate controlled cortical impact in mice. The protective effect of curcumin was associated with a significant attenuation in the acute pericontusional expression of interleukin-1beta, a pro-inflammatory cytokine, after injury. Curcumin also reversed the induction of aquaporin-4, an astrocytic water channel implicated in the development of cellular edema following head trauma. Notably, curcumin blocked IL-1beta-induced aquaporin-4 expression in cultured astrocytes, an effect mediated, at least in part, by reduced activation of the p50 and p65 subunits of nuclear factor kappaB. Consistent with this notion, curcumin preferentially attenuated phosphorylated p65 immunoreactivity in pericontusional astrocytes and decreased the expression of glial fibrillary acidic protein, a reactive astrocyte marker. As a whole, these data suggest clinically achievable concentrations of curcumin reduce glial activation and cerebral edema following neurotrauma, a finding which warrants further investigation.
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PMID:Curcumin attenuates cerebral edema following traumatic brain injury in mice: a possible role for aquaporin-4? 2013 69


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