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

Although the etiology of hypertension-related organ damage remains poorly understood, it has recently been proposed that activated and adherent leukocytes may contribute to the pathogenesis of progressive organ injury in hypertension. The objective of this study was to determine whether the adherence and emigration of leukocytes in microvessels differ between spontaneously hypertensive and normotensive rats. Leukocyte adherence, rolling, and emigration as well as vessel diameter and erythrocyte velocity were monitored in mesenteric venules of age-matched normotensive and hypertensive rats. Measurements were obtained under baseline conditions and during superfusion of the mesentery with either platelet activating factor, leukotriene B4, or NG-nitro-L-arginine-methyl ester, an inhibitor of nitric oxide synthesis. Tissue-associated myeloperoxidase activity, an index of the total tissue granulocyte population, was measured in various tissues of normotensive and hypertensive rats. Systemic arterial pressure and the circulating polymorphonuclear leukocyte count were elevated in hypertensive relative to normotensive rats. The number of adherent and emigrated leukocytes under baseline conditions did not differ between normotensive and hypertensive rats. Although the nitric oxide synthase inhibitor caused a similar rise in leukocyte adherence and emigration in both rat strains, the adhesive interactions elicited by either platelet activating factor or leukotriene B4 were significantly blunted in hypertensive relative to normotensive rats. Flow cytometric analysis of whole-blood samples revealed a lower surface expression of CD11b/CD18 on leukocytes from hypertensive rats under stimulated conditions. Myeloperoxidase activity in mesentery and small and large intestine was low, whereas lung, spleen, and stomach values were high in hypertensive compared with normotensive rats.(ABSTRACT TRUNCATED AT 250 WORDS)
Hypertension 1993 May
PMID:Leukocyte-endothelial cell adhesion in spontaneously hypertensive and normotensive rats. 838 61

Endothelial cell activation is important in the pathogenesis of preeclampsia; however, the nature of the activation is unknown. We investigated 22 patients with preeclampsia. 29 normotensive pregnancies, and 18 nonpregnant women to test the hypothesis that serum from preeclamptic patients induces expression of intercellular adhesion molecule-1 (ICAM-1) and vascular adhesion molecule-1 (VCAM-1) and stimulates intracellular free calcium concentrations [Ca2+]i in cultured endothelial cells. We then asked whether the corresponding integrin adhesive counter receptors lymphocyte function-associated antigen-1 (CD11a/CD18), macrophage-1 antigen (CD11b/CD18), p150,95 (CD11c/CD18), and very late activation antigen-4 (CD49/CD29) are increased in patients with preeclampsia. In the pregnant women, the measurements were conducted both before and after delivery. Integrin expression was measured by fluorescent antibody cell sorting analysis using monoclonal antibodies. ICAM-1 and VCAM-1 were analyzed on endothelial cells by enzyme-linked immunosorbent assay. [Ca2+]i was measured with fura 2. Serum from preeclamptic patients increased endothelial cell ICAM-1 expression but not VCAM-1 expression. Preeclamptic patients' serum also increased [Ca2+]i in endothelial cells compared with serum from normal nonpregnant or normal pregnant women. Endothelial cell [Ca2+]i concentrations were correlated with the ICAM-1 expression in preeclamptic patients (r = .80, P < .001) before but not after delivery. Expression of the integrin counter receptors on leukocytes was similarly increased in preclampsia and normal pregnancy compared with the nonpregnant state. The expression decreased significantly after delivery in both groups. Our results demonstrate that serum from preeclamptic women induces increased ICAM-1 surface expression on endothelial cells, while the expression of the integrin counterreceptors was not different. The effect on endothelial cells may be related to an increase in [Ca2+]i. The effect on cultured endothelial cells and the rapid decrease after delivery suggests the presence of a circulating serum factor which increases endothelial cell [Ca2+]i and enhances adhesion molecule expression.
Hypertension 1997 Jan
PMID:Endothelial adhesion molecules and leukocyte integrins in preeclamptic patients. 903 17

Defective exocytosis could underlie clinical and metabolic abnormalities in Type 2 diabetes. Because many SNARE proteins appear to be common mediators of exocytosis, we examined phorbol myristate acetate-stimulated expression of CD11b and CD69 on polymorphonuclear leukocytes (PMN) from Type 2 diabetic subjects with hypertension and microalbuminuria (D-htma), hypertension only (D-ht) or uncomplicated (D-uc), and normal controls (NC) by flow cytometry. CD11b expression was rapid (half maximal by 7 min), initially on all PMN. CD69 expression took place subsequently but on PMN that did not express CD11b. The proportion of CD11b-positive PMN at 30 min was higher in all diabetic groups than in NC. Expression of CD11b was higher and CD69 lower in D-uc and D-htma but were similar in NC and D-ht. In Type 2 diabetes the transition from the CD11b-positive to CD69-positive state is impaired. The defect in the process of CD69 expression appeared most marked in diabetic subjects with hypertension and microalbuminuria.
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PMID:Dysregulation of PMN antigen expression in Type 2 diabetes may reflect a generalized defect of exocytosis: influence of hypertension and microalbuminuria. 1038 Sep 2

The effect of venous hypertension on the state of activation of leucocytes has been investigated in patients with venous disease and control subjects. Leucocytes become 'trapped' in the circulation of the leg during periods of venous hypertension produced by sitting or standing. This is greater in the limbs of patients with chronic venous disease than controls. Studies of the plasma levels of neutrophil granule enzymes show that these are increased during periods of venous hypertension, suggesting that this causes activation of the neutrophils. Investigation of the leucocyte surface ligand CD11b shows that the more activated neutrophils and monocytes are sequestered during venous hypertension. Measurement of plasma levels of the soluble parts of the vascular (VCAM), intercellular (ICAM) and endothelial leucocyte (ELAM) adhesion molecules show that these are all elevated in patients with chronic venous disease compared to controls. Following 30 min of venous hypertension produced by standing, these levels are further increased. These data suggest that venous hypertension causes neutrophil and monocyte activation, which in turn causes injury to the endothelium. I believe that this may be the mechanism that initiates the pathological processes which lead to venous ulceration. It has recently been shown that the venotonic drug Daflon 500 mg (450 mg diosmin, 50 mg hesperidin, Servier, France) influences these processes. Surface expression of CD62L is reduced in neutrophils and monocytes, and plasma levels of soluble endothelial adhesion molecules are reduced. These observations may explain the anti-inflammatory effects of Daflon 500 mg.
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PMID:Neutrophil activation and mediators of inflammation in chronic venous insufficiency. 1047 48

The purpose of this research was to obtain further information about the role of polymorphonuclear leukocytes in essential hypertension. These cells could be involved in the pathogenesis of organ injury. Thirty subjects (14 men and 16 women) with essential hypertension were enrolled. In these subjects we determined, at baseline and after in vitro activation with 4-phorbol 12-myristate 13-acetate and N:-formyl-methionyl-leucyl-phenylalanine, the polymorphonuclear leukocyte membrane fluidity, obtained by labeling the cells with 1-[4-(trimethylamino)phenyl]-6-phenyl-1,3, 5-hexatriene, cytosolic Ca(2+) concentration, obtained by marking the cells with Fura 2-AM, and integrin pattern (CD11a, CD11b, CD11c, and CD18), by using the indirect immunofluorescence with a flow cytometer. At baseline there was no difference in membrane fluidity between normal subjects and hypertensives, whereas hypertensives showed an increase in cytosolic Ca(2+) content and an increase of the phenotypical expression of CD11a, CD11b, and CD18. In normal subjects and in hypertensives, after activation, no variation was found in membrane fluidity and cytosolic Ca(2+) content. In normal subjects, after activation, we observed a significant increase of the expression of all adhesion molecules, whereas in hypertensives we found an increase of the expression of CD11b, CD11c, and CD18 but also a decrease of CD11a. The behavior of the polymorphonuclear leukocyte integrin profile may have several explanations, and in particular, the trend of CD11a after chemotactic activation may be related to its cleavage or to an altered integrin phosphorylation/dephosphorylation balance hypothetically present in this clinical condition.
Hypertension 2000 Nov
PMID:Polymorphonuclear integrins, membrane fluidity, and cytosolic Ca(2+) content after activation in essential hypertension. 1108 48

The elevated ambulatory pressure in the peripheral venous system of chronic venous insufficiency (CVI) patients manifests itself not only in the form of disturbed macrocirculation but also and particularly in microangiopathic changes. For this reason, it is closely correlated with trophic disorders of the skin and can ultimately lead to ulceration. Using microcirculation research techniques, we are able to provide clear evidence of a typical microangiopathy in chronic venous insufficiency. Fifty CVI in Widmer stages I, II, and III were examined with fluorescence video microscopy, intravital video capillaroscopy, transcutaneous oxygen partial pressure measurement, TcpO2 and laser Doppler flowmetry. The effects of compression therapy with individually fitted compression stockings on capillary morphology were studied over a period of 4 weeks in 20 CVI patients in Widmer stages I and II. The capillary pressure was measured during simulated muscle contraction using a servo-null micropressure system. We periodically drew blood from the dorsalis pedis vein and a brachial vein of 11 healthy test persons and 8 patients with stage III CVI during experimental venous hypertension in order to evaluate the expression pattern of leukocyte adhesion molecules involved in inflammation: LFA-1 (CD11a), Mac-1 (CD11b), p150,95 (CD11c), CD18, VLA-4 (CD49d), and L-selectin (CD62L). In the same patients, we used immunohistochemical methods to examine clinically unaffected skin and the skin near an ulcer, focusing on the adhesion molecules ICAM-1, VCAM-1, and E-selectin. The microangiopathic changes observed with worsening clinical symptoms include a decrease in the number of capillaries, glomerulus-like changes in capillary morphology, a drop in the oxygen content (tcpO2) of the skin, increased permeability of the capillaries to low-molecular-weight substances, increased laser Doppler flux reflecting elevated subcutaneous flow, and diminished vascular reserve. These microangiopathic changes worsen in linear proportion to the clinical severity of chronic venous insufficiency. In patients with venous ulcerations, the baseline expression of LFA-1 and VLA-4 on lymphocytes, Mac-1 expression on the myeloid cell line, and L-selectin expression on all three cell lines was not significantly different form that in healthy controls. During orthostatic stress, there was a significant reduction in the expression of L-selectin in blood cells collected at foot level in the controls (p=0.002), but not in the patients. Clinical improvement by compression therapy was accompanied by an increase in the number of nutritive capillaries, while the diameter of the capillaries and the dermal papillae was reduced. When ulcers healed in a short period (<6 weeks), we observed a concomitant increase in the number of capillaries (p<0.05). Microangiopathy appears before tropic disorders of the skin develop. Even trophically normal skin areas may have dilated nutritive capillaries, an early sign of disturbed skin perfusion. These changes represent a plausible explanation for the development and to recurrency tendency of venous ulcers. The reduced expression of lymphocytic L-selectin in healthy controls during the orthostatic stress test may be an indication that the cells are activated by venous stasis. Clinically effective therapeutic measures improve the impaired microcirculation of the skin in the ankle area.
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PMID:Microcirculatory dysfunction in chronic venous insufficiency (CVI). 1115 69

Neutrophil activation occurs in women with preeclampsia and is resolved after delivery. The present study examined whether circulating factors in plasma of women with preeclampsia caused neutrophil activation and lipid peroxidation. Twenty-one women with proteinuric preeclampsia were matched for age and gestational age with 19 normal pregnant women. Plasma was collected from all subjects before delivery and at 6 weeks postpartum and incubated with autologous white-cell buffy coat collected at the postpartum visit. Neutrophil activation was assessed by level of CD11b and CD18 expression after incubation with autologous antepartum or postpartum plasma. Lipid peroxidation was assessed by measurement of F(2)-isoprostanes in plasma, plasma-white cell incubates, and urine. Neutrophil CD11b and CD18 expression was not differentially altered by incubation with plasma from either women with preeclampsia or normal pregnant women and was similar between groups when incubation was performed with plasma collected after delivery. In preeclampsia, plasma F(2)-isoprostanes were significantly increased before and after delivery compared with controls. Plasma F(2)-isoprostanes were increased 2-fold after incubation of plasma with buffy coat, but preeclamptic women had higher levels compared with those of controls when either pregnant or postpartum plasma was used. In pregnant preeclamptics, plasma F(2)-isoprostanes were positively correlated with lymphocyte count. Six weeks after delivery, plasma F(2)-isoprostanes in the preeclamptic women were significantly positively associated with lymphocyte count and cholesterol and negatively associated with albumin. In conclusion, the present study does not suggest that a stable circulating factor causes neutrophil activation in preeclampsia. However, lipid peroxidation is elevated before and after delivery in women with preeclampsia, which suggests that these women may have an underlying predisposition to increased oxidative stress that may be driven by or contribute to a persistent low-grade inflammatory response.
Hypertension 2001 Oct
PMID:Study of plasma factors associated with neutrophil activation and lipid peroxidation in preeclampsia. 1164 Dec 90

In this study we analysed blood samples taken from the dorsalis pedis vein and a brachial vein of 11 healthy test persons and 8 patients with venous leg ulcer under experimental venous hypertension in order to examine changes in the expression of leukocyte adhesion molecules (LFA-1 (CD11a), Mac-1 (CD11b), p150,95 (CD11c), CD18, VLA-4 (CD49d) and L-selectin (CD62L)) which are involved in the adhesion steps of leukocytes to endothelial cells for transmigration into tissues. Under orthostatic stress, lymphocytes in controls collected at the foot level showed a significant reduction in the expression of L-selectin (p=0.002), compared to those of patients. This finding suggests that venous stasis negatively influences the expression of L-selectin on leukocytes only in healthy volunteers. Patients with chronic venous insufficiency seem to suffer from a specific defect in the regulation of L-selectin shedding under orthostatic stress.
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PMID:Dysregulated L-selectin expression on lymphocytes in patients with chronic venous insufficiency. 1179 Aug 67

Endothelial dysfunction and inflammation appear to play a major role in the pathogenesis of preeclampsia. We hypothesize that a chronic inflammation in the decidua and placenta during preeclampsia may lead to a local leukocyte activation in this compartment. Venous blood was sampled simultaneously from antecubital and uterine veins during cesarean sections in 30 women with preeclampsia, 29 with uncomplicated pregnancies, and from 17 nonpregnant women. The expression of adhesion molecules and complement-related markers on neutrophils and monocytes was analyzed by flow cytometry. In patients with preeclampsia, neutrophil expression of the integrins CD11a, CD11b, and CD11c and of the complement related markers CD35 and CD59 was significantly higher in samples from uterine than from antecubital veins. No differences were found in nonpregnant women. On monocytes the expression of the Sialyl Lewis(x) antigen, the integrins CD11a, CD11c, and CD49d, and the complement-related markers CD46 and CD59 was higher in samples from uterine than from antecubital veins during preeclampsia, but not in uncomplicated pregnancies, whereas in nonpregnant women CD31 was decreased. Our findings suggest activation of neutrophils and monocytes taking place during the uteroplacental passage in preeclamptic, but not in normal pregnancies. Such a local inflammatory response involving enhanced leukocyte/endothelial interaction may contribute to the pathogenesis of this disorder.
Hypertension 2002 Jan
PMID:Activation of leukocytes during the uteroplacental passage in preeclampsia. 1179 95

At a given degree of adiposity, metabolic and cardiovascular risk varies markedly between individuals. Animal studies suggest that differentially expressed systemic activation of monocytes contributes to the obesity-associated risk variability. We tested the hypothesis that systemic monocyte activation is associated with changes in adipose tissue and skeletal muscle metabolism. In 17 obese hypertensive patients, we assessed CD11b expression on circulating monocytes, gene expression in adipose tissue biopsies, and obtained blood samples and adipose tissue and skeletal muscle microdialysis samples in the fasted state and during a glucose load. Patients were stratified into groups with higher and lower CD11b expression on monocytes. Expression of the macrophage marker CD68 was increased markedly in adipose tissue of subjects with higher CD11b expression. Although no differences in systemic insulin sensitivity were found between both groups, patients with higher peripheral CD11b expression showed a markedly augmented increase in dialysate glucose in adipose tissue during oral glucose tolerance testing and increased adipose tissue lipolysis as well. Our data demonstrate that human monocyte activation is associated with tissue-specific changes in glucose and lipid metabolism. These findings may be explained in part by monocyte/macrophage infiltration of adipose tissue, which appears to interfere with insulin responsiveness.
Hypertension 2005 Jul
PMID:Adipose tissue metabolism and CD11b expression on monocytes in obese hypertensives. 1597 67


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